. Update the Copyright year (only) when changing content.
. /////////////////////////////////////////////////////////////////////////////
-.set previousversion "4.80"
+.set previousversion "4.86"
.include ./local_params
.set ACL "access control lists (ACLs)"
.set I " "
.macro copyyear
-2014
+2015
.endmacro
. /////////////////////////////////////////////////////////////////////////////
waiting for it by the time it recovers, and sending them in a single SMTP
connection is clearly beneficial. Whenever a delivery to a remote host is
deferred,
-.cindex "hints database"
+.cindex "hints database" "deferred deliveries"
Exim makes a note in its hints database, and whenever a successful
SMTP delivery has happened, it looks to see if any other messages are waiting
for the same host. If any are found, they are sent over the same SMTP
in the ASCII character set, and to label them as being in a particular
character set. When Exim is inspecting header lines by means of the &%$h_%&
mechanism, it decodes them, and translates them into a specified character set
-(default ISO-8859-1). The translation is possible only if the operating system
+(default is set at build time). The translation is possible only if the operating system
supports the &[iconv()]& function.
However, some of the operating systems that supply &[iconv()]& do not support
defined. AAAA records (analogous to A records for IPv4) are in use, and are
currently seen as the mainstream. Another record type called A6 was proposed
as better than AAAA because it had more flexibility. However, it was felt to be
-over-complex, and its status was reduced to &"experimental"&. It is not known
-if anyone is actually using A6 records. Exim has support for A6 records, but
-this is included only if you set &`SUPPORT_A6=YES`& in &_Local/Makefile_&. The
-support has not been tested for some time.
+over-complex, and its status was reduced to &"experimental"&.
+Exim used to
+have a compile option for including A6 record support but this has now been
+withdrawn.
.cindex "symbolic link" "to source files"
Symbolic links to relevant source files are installed in the build directory.
-&*Warning*&: The &%-j%& (parallel) flag must not be used with &'make'&; the
-building process fails if it is set.
-
If this is the first time &'make'& has been run, it calls a script that builds
a make file inside the build directory, using the configuration files from the
&_Local_& directory. The new make file is then passed to another instance of
.code
mysql_servers = <value not displayable>
.endd
-If &%configure_file%& is given as an argument, the name of the run time
-configuration file is output.
+If &%config%& is given as an argument, the config is
+output, as it was parsed, any include file resolved, any comment removed.
+
+If &%config_file%& is given as an argument, the name of the run time
+configuration file is output. (&%configure_file%& works too, for
+backward compatibility.)
If a list of configuration files was supplied, the value that is output here
is the name of the file that was actually used.
exim '-D ABC = something' ...
.endd
&%-D%& may be repeated up to 10 times on a command line.
+.new
+Only macro names up to 22 letters long can be set.
+.wen
.vitem &%-d%&<&'debug&~options'&>
by Exim in conjunction with the &%-MC%& option. It signifies that the
connection to the remote host has been authenticated.
+.vitem &%-MCD%&
+.oindex "&%-MCD%&"
+This option is not intended for use by external callers. It is used internally
+by Exim in conjunction with the &%-MC%& option. It signifies that the
+remote host supports the ESMTP &_DSN_& extension.
+
.vitem &%-MCP%&
.oindex "&%-MCP%&"
This option is not intended for use by external callers. It is used internally
using the same syntax as for &%-oMa%&. The interface address is placed in
&$received_ip_address$& and the port number, if present, in &$received_port$&.
+.vitem &%-oMm%&&~<&'message&~reference'&>
+.oindex "&%-oMm%&"
+.cindex "message reference" "message reference, specifying for local message"
+See &%-oMa%& above for general remarks about the &%-oM%& options. The &%-oMm%&
+option sets the message reference, e.g. message-id, and is logged during
+delivery. This is useful when some kind of audit trail is required to tie
+messages together. The format of the message reference is checked and will
+abort if the format is invalid. The option will only be accepted if exim is
+running in trusted mode, not as any regular user.
+
+The best example of a message reference is when Exim sends a bounce message.
+The message reference is the message-id of the original message for which Exim
+is sending the bounce.
+
.vitem &%-oMr%&&~<&'protocol&~name'&>
.oindex "&%-oMr%&"
.cindex "protocol, specifying for local message"
.oindex "&%-X%&"
This option is interpreted by Sendmail to cause debug information to be sent
to the named file. It is ignored by Exim.
+
+.vitem &%-z%&&~<&'log-line'&>
+.oindex "&%-z%&"
+This option writes its argument to Exim's logfile.
+Use is restricted to administrators; the intent is for operational notes.
+Quotes should be used to maintain a multi-word item as a single argument,
+under most shells.
.endlist
.ecindex IIDclo1
Exim's configuration file is divided into a number of different parts. General
option settings must always appear at the start of the file. The other parts
are all optional, and may appear in any order. Each part other than the first
-is introduced by the word &"begin"& followed by the name of the part. The
-optional parts are:
+is introduced by the word &"begin"& followed by at least one literal
+space, and the name of the part. The optional parts are:
.ilist
&'ACL'&: Access control lists for controlling incoming SMTP mail (see chapter
message_size_limit = 100M
.endif
.endd
-sets a message size limit of 50M if the macro &`AAA`& is defined, and 100M
+sets a message size limit of 50M if the macro &`AAA`& is defined
+(or &`A`& or &`AA`&), and 100M
otherwise. If there is more than one macro named on the line, the condition
is true if any of them are defined. That is, it is an &"or"& condition. To
obtain an &"and"& condition, you need to use nested &`.ifdef`&s.
colon in the example above is necessary. If it were not there, the list would
be interpreted as the two items 127.0.0.1:: and 1.
-.section "Changing list separators" "SECID53"
+.section "Changing list separators" "SECTlistsepchange"
.cindex "list separator" "changing"
.cindex "IPv6" "addresses in lists"
Doubling colons in IPv6 addresses is an unwelcome chore, so a mechanism was
1413 (hence their names):
.code
rfc1413_hosts = *
-rfc1413_query_timeout = 5s
+rfc1413_query_timeout = 0s
+.endd
+These settings cause Exim to avoid ident callbacks for all incoming SMTP calls.
+Few hosts offer RFC1413 service these days; calls have to be
+terminated by a timeout and this needlessly delays the startup
+of an incoming SMTP connection.
+If you have hosts for which you trust RFC1413 and need this
+information, you can change this.
+
+This line enables an efficiency SMTP option. It is negotiated by clients
+and not expected to cause problems but can be disabled if needed.
+.code
+prdr_enable = true
.endd
-These settings cause Exim to make ident callbacks for all incoming SMTP calls.
-You can limit the hosts to which these calls are made, or change the timeout
-that is used. If you set the timeout to zero, all ident calls are disabled.
-Although they are cheap and can provide useful information for tracing problem
-messages, some hosts and firewalls have problems with ident calls. This can
-result in a timeout instead of an immediate refused connection, leading to
-delays on starting up an incoming SMTP session.
When Exim receives messages over SMTP connections, it expects all addresses to
be fully qualified with a domain, as required by the SMTP definition. However,
show how you can specify hosts that are permitted to send unqualified sender
and recipient addresses, respectively.
+The &%log_selector%& option is used to increase the detail of logging
+over the default:
+.code
+log_selector = +smtp_protocol_error +smtp_syntax_error \
+ +tls_certificate_verified
+.endd
+
The &%percent_hack_domains%& option is also commented out:
.code
# percent_hack_domains =
.code
remote_smtp:
driver = smtp
+ hosts_try_prdr = *
.endd
-This transport is used for delivering messages over SMTP connections. All its
-options are defaulted. The list of remote hosts comes from the router.
+This transport is used for delivering messages over SMTP connections.
+The list of remote hosts comes from the router.
+The &%hosts_try_prdr%& option enables an efficiency SMTP option.
+It is negotiated between client and server
+and not expected to cause problems but can be disabled if needed.
+All other options are defaulted.
.code
local_delivery:
driver = appendfile
.endd
This transport is used for handling deliveries to pipes that are generated by
redirection (aliasing or users' &_.forward_& files). The &%return_output%&
-option specifies that any output generated by the pipe is to be returned to the
-sender.
+option specifies that any output on stdout or stderr generated by the pipe is to
+be returned to the sender.
.code
address_file:
driver = appendfile
lookup. Lookups of this type are conditional expansion items. Different results
can be defined for the cases of lookup success and failure. See chapter
&<<CHAPexpand>>&, where string expansions are described in detail.
+The key for the lookup is specified as part of the string expansion.
.next
Lists of domains, hosts, and email addresses can contain lookup requests as a
way of avoiding excessively long linear lists. In this case, the data that is
returned by the lookup is often (but not always) discarded; whether the lookup
succeeds or fails is what really counts. These kinds of list are described in
chapter &<<CHAPdomhosaddlists>>&.
+The key for the lookup is given by the context in which the list is expanded.
.endlist
String expansions, lists, and lookups interact with each other in such a way
&`fail`& keyword causes a &'forced expansion failure'& &-- see section
&<<SECTforexpfai>>& for an explanation of what this means.
-The supported DNS record types are A, CNAME, MX, NS, PTR, SPF, SRV, TLSA and TXT,
-and, when Exim is compiled with IPv6 support, AAAA (and A6 if that is also
-configured). If no type is given, TXT is assumed. When the type is PTR,
+The supported DNS record types are A, CNAME, MX, NS, PTR, SOA, SPF, SRV, TLSA
+and TXT, and, when Exim is compiled with IPv6 support, AAAA.
+If no type is given, TXT is assumed.
+
+For any record type, if multiple records are found, the data is returned as a
+concatenation, with newline as the default separator. The order, of course,
+depends on the DNS resolver. You can specify a different separator character
+between multiple records by putting a right angle-bracket followed immediately
+by the new separator at the start of the query. For example:
+.code
+${lookup dnsdb{>: a=host1.example}}
+.endd
+It is permitted to specify a space as the separator character. Further
+white space is ignored.
+For lookup types that return multiple fields per record,
+an alternate field separator can be specified using a comma after the main
+separator character, followed immediately by the field separator.
+
+.cindex "PTR record" "in &(dnsdb)& lookup"
+When the type is PTR,
the data can be an IP address, written as normal; inversion and the addition of
&%in-addr.arpa%& or &%ip6.arpa%& happens automatically. For example:
.code
For an MX lookup, both the preference value and the host name are returned for
each record, separated by a space. For an SRV lookup, the priority, weight,
port, and host name are returned for each record, separated by spaces.
-
-For any record type, if multiple records are found (or, for A6 lookups, if a
-single record leads to multiple addresses), the data is returned as a
-concatenation, with newline as the default separator. The order, of course,
-depends on the DNS resolver. You can specify a different separator character
-between multiple records by putting a right angle-bracket followed immediately
-by the new separator at the start of the query. For example:
-.code
-${lookup dnsdb{>: a=host1.example}}
-.endd
-It is permitted to specify a space as the separator character. Further
-white space is ignored.
+The field separator can be modified as above.
.cindex "TXT record" "in &(dnsdb)& lookup"
.cindex "SPF record" "in &(dnsdb)& lookup"
For TXT records with multiple items of data, only the first item is returned,
-unless a separator for them is specified using a comma after the separator
-character followed immediately by the TXT record item separator. To concatenate
-items without a separator, use a semicolon instead. For SPF records the
+unless a field separator is specified.
+To concatenate items without a separator, use a semicolon instead.
+For SPF records the
default behaviour is to concatenate multiple items without using a separator.
.code
${lookup dnsdb{>\n,: txt=a.b.example}}
It is permitted to specify a space as the separator character. Further
white space is ignored.
+.cindex "SOA record" "in &(dnsdb)& lookup"
+For an SOA lookup, while no result is obtained the lookup is redone with
+successively more leading components dropped from the given domain.
+Only the primary-nameserver field is returned unless a field separator is
+specified.
+.code
+${lookup dnsdb{>:,; soa=a.b.example.com}}
+.endd
+
+.section "Dnsdb lookup modifiers" "SECTdnsdb_mod"
+.cindex "dnsdb modifiers"
+.cindex "modifiers" "dnsdb"
+.cindex "options" "dnsdb"
+Modifiers for &(dnsdb)& lookups are given by optional keywords,
+each followed by a comma,
+that may appear before the record type.
+
+The &(dnsdb)& lookup fails only if all the DNS lookups fail. If there is a
+temporary DNS error for any of them, the behaviour is controlled by
+a defer-option modifier.
+The possible keywords are
+&"defer_strict"&, &"defer_never"&, and &"defer_lax"&.
+With &"strict"& behaviour, any temporary DNS error causes the
+whole lookup to defer. With &"never"& behaviour, a temporary DNS error is
+ignored, and the behaviour is as if the DNS lookup failed to find anything.
+With &"lax"& behaviour, all the queries are attempted, but a temporary DNS
+error causes the whole lookup to defer only if none of the other lookups
+succeed. The default is &"lax"&, so the following lookups are equivalent:
+.code
+${lookup dnsdb{defer_lax,a=one.host.com:two.host.com}}
+${lookup dnsdb{a=one.host.com:two.host.com}}
+.endd
+Thus, in the default case, as long as at least one of the DNS lookups
+yields some data, the lookup succeeds.
+
+.cindex "DNSSEC" "dns lookup"
+Use of &(DNSSEC)& is controlled by a dnssec modifier.
+The possible keywords are
+&"dnssec_strict"&, &"dnssec_lax"&, and &"dnssec_never"&.
+With &"strict"& or &"lax"& DNSSEC information is requested
+with the lookup.
+With &"strict"& a response from the DNS resolver that
+is not labelled as authenticated data
+is treated as equivalent to a temporary DNS error.
+The default is &"never"&.
+
+See also the &$lookup_dnssec_authenticated$& variable.
+
+.cindex timeout "dns lookup"
+.cindex "DNS" timeout
+Timeout for the dnsdb lookup can be controlled by a retrans modifier.
+The form is &"retrans_VAL"& where VAL is an Exim time specification
+(e.g. &"5s"&).
+The default value is set by the main configuration option &%dns_retrans%&.
+
+Retries for the dnsdb lookup can be controlled by a retry modifier.
+The form if &"retry_VAL"& where VAL is an integer.
+The default count is set by the main configuration option &%dns_retry%&.
+
+.new
+.cindex cacheing "of dns lookup"
+.cindex TTL "of dns lookup"
+.cindex DNS TTL
+Dnsdb lookup results are cached within a single process (and its children).
+The cache entry lifetime is limited to the smallest time-to-live (TTL)
+value of the set of returned DNS records.
+.wen
+
+
.section "Pseudo dnsdb record types" "SECID66"
.cindex "MX record" "in &(dnsdb)& lookup"
By default, both the preference value and the host name are returned for
authorization required but absent, or &"?"& for unknown.
.cindex "A+" "in &(dnsdb)& lookup"
-The pseudo-type A+ performs an A6 lookup (if configured) followed by an AAAA
+The pseudo-type A+ performs an AAAA
and then an A lookup. All results are returned; defer processing
(see below) is handled separately for each lookup. Example:
.code
in the same way that multiple DNS records for a single item are handled. A
different separator can be specified, as described above.
-Modifiers for &(dnsdb)& lookups are givien by optional keywords,
-each followed by a comma,
-that may appear before the record type.
-
-The &(dnsdb)& lookup fails only if all the DNS lookups fail. If there is a
-temporary DNS error for any of them, the behaviour is controlled by
-a defer-option modifier.
-The possible keywords are
-&"defer_strict"&, &"defer_never"&, and &"defer_lax"&.
-With &"strict"& behaviour, any temporary DNS error causes the
-whole lookup to defer. With &"never"& behaviour, a temporary DNS error is
-ignored, and the behaviour is as if the DNS lookup failed to find anything.
-With &"lax"& behaviour, all the queries are attempted, but a temporary DNS
-error causes the whole lookup to defer only if none of the other lookups
-succeed. The default is &"lax"&, so the following lookups are equivalent:
-.code
-${lookup dnsdb{defer_lax,a=one.host.com:two.host.com}}
-${lookup dnsdb{a=one.host.com:two.host.com}}
-.endd
-Thus, in the default case, as long as at least one of the DNS lookups
-yields some data, the lookup succeeds.
-
-Use of &(DNSSEC)& is controlled by a dnssec modifier.
-The possible keywords are
-&"dnssec_strict"&, &"dnssec_lax"&, and &"dnssec_never"&.
-With &"strict"& or &"lax"& DNSSEC information is requested
-with the lookup.
-With &"strict"& a response from the DNS resolver that
-is not labelled as authenticated data
-is treated as equivalent to a temporary DNS error.
-The default is &"never"&.
-
LDAP connections, rather than the SSL-on-connect &`ldaps`&.
See the &%ldap_start_tls%& option.
-.new
Starting with Exim 4.83, the initialization of LDAP with TLS is more tightly
controlled. Every part of the TLS configuration can be configured by settings in
&_exim.conf_&. Depending on the version of the client libraries installed on
running as could affect which config files it read. With Exim 4.83, these
methods become optional, only taking effect if not specifically set in
&_exim.conf_&.
-.wen
.section "LDAP quoting" "SECID68"
&`USER `& set the DN, for authenticating the LDAP bind
&`PASS `& set the password, likewise
&`REFERRALS `& set the referrals parameter
-.new
&`SERVERS `& set alternate server list for this query only
-.wen
&`SIZE `& set the limit for the number of entries returned
&`TIME `& set the maximum waiting time for a query
.endd
must be &"follow"& (the default) or &"nofollow"&. The latter stops the LDAP
library from trying to follow referrals issued by the LDAP server.
+.cindex LDAP timeout
+.cindex timeout "LDAP lookup"
The name CONNECT is an obsolete name for NETTIME, retained for
backwards compatibility. This timeout (specified as a number of seconds) is
enforced from the client end for operations that can be carried out over a
The TIME parameter (also a number of seconds) is passed to the server to
set a server-side limit on the time taken to complete a search.
-.new
The SERVERS parameter allows you to specify an alternate list of ldap servers
-to use for an individual lookup. The global ldap_servers option provides a
+to use for an individual lookup. The global &%ldap_default_servers%& option provides a
default list of ldap servers, and a single lookup can specify a single ldap
server to use. But when you need to do a lookup with a list of servers that is
different than the default list (maybe different order, maybe a completely
different set of servers), the SERVERS parameter allows you to specify this
-alternate list.
-.wen
+alternate list (colon-separated).
Here is an example of an LDAP query in an Exim lookup that uses some of these
values. This is a single line, folded to fit on the page:
The &(ldapdn)& lookup type returns the Distinguished Name from a single entry
as a sequence of values, for example
.code
-cn=manager, o=University of Cambridge, c=UK
+cn=manager,o=University of Cambridge,c=UK
.endd
The &(ldap)& lookup type generates an error if more than one entry matches the
search filter, whereas &(ldapm)& permits this case, and inserts a newline in
In the common case where you specify a single attribute in your LDAP query, the
result is not quoted, and does not contain the attribute name. If the attribute
-has multiple values, they are separated by commas.
+has multiple values, they are separated by commas. Any comma that is
+part of an attribute's value is doubled.
If you specify multiple attributes, the result contains space-separated, quoted
strings, each preceded by the attribute name and an equals sign. Within the
quotes, the quote character, backslash, and newline are escaped with
backslashes, and commas are used to separate multiple values for the attribute.
+Any commas in attribute values are doubled
+(permitting treatment of the values as a comma-separated list).
Apart from the escaping, the string within quotes takes the same form as the
output when a single attribute is requested. Specifying no attributes is the
same as specifying all of an entry's attributes.
Here are some examples of the output format. The first line of each pair is an
LDAP query, and the second is the data that is returned. The attribute called
-&%attr1%& has two values, whereas &%attr2%& has only one value:
+&%attr1%& has two values, one of them with an embedded comma, whereas
+&%attr2%& has only one value. Both attributes are derived from &%attr%&
+(they have SUP &%attr%& in their schema definitions).
+
.code
ldap:///o=base?attr1?sub?(uid=fred)
-value1.1, value1.2
+value1.1,value1,,2
ldap:///o=base?attr2?sub?(uid=fred)
value two
+ldap:///o=base?attr?sub?(uid=fred)
+value1.1,value1,,2,value two
+
ldap:///o=base?attr1,attr2?sub?(uid=fred)
-attr1="value1.1, value1.2" attr2="value two"
+attr1="value1.1,value1,,2" attr2="value two"
ldap:///o=base??sub?(uid=fred)
-objectClass="top" attr1="value1.1, value1.2" attr2="value two"
+objectClass="top" attr1="value1.1,value1,,2" attr2="value two"
.endd
-The &%extract%& operator in string expansions can be used to pick out
-individual fields from data that consists of &'key'&=&'value'& pairs. You can
+You can
make use of Exim's &%-be%& option to run expansion tests and thereby check the
results of LDAP lookups.
+The &%extract%& operator in string expansions can be used to pick out
+individual fields from data that consists of &'key'&=&'value'& pairs.
+The &%listextract%& operator should be used to pick out individual values
+of attributes, even when only a single value is expected.
+The doubling of embedded commas allows you to use the returned data as a
+comma separated list (using the "<," syntax for changing the input list separator).
found, but that is still a successful query. In other words, the list of
servers provides a backup facility, not a list of different places to look.
+.new
The &%quote_mysql%&, &%quote_pgsql%&, and &%quote_oracle%& expansion operators
convert newline, tab, carriage return, and backspace to \n, \t, \r, and \b
respectively, and the characters single-quote, double-quote, and backslash
-itself are escaped with backslashes. The &%quote_pgsql%& expansion operator, in
-addition, escapes the percent and underscore characters. This cannot be done
-for MySQL because these escapes are not recognized in contexts where these
-characters are not special.
+itself are escaped with backslashes.
+.wen
.section "Specifying the server in the query" "SECTspeserque"
For MySQL and PostgreSQL lookups (but not currently for Oracle and InterBase),
.section "Special MySQL features" "SECID73"
For MySQL, an empty host name or the use of &"localhost"& in &%mysql_servers%&
causes a connection to the server on the local host by means of a Unix domain
-socket. An alternate socket can be specified in parentheses. The full syntax of
-each item in &%mysql_servers%& is:
+socket. An alternate socket can be specified in parentheses.
+.new
+An option group name for MySQL option files can be specified in square brackets;
+the default value is &"exim"&.
+.wen
+The full syntax of each item in &%mysql_servers%& is:
.display
-<&'hostname'&>::<&'port'&>(<&'socket name'&>)/<&'database'&>/&&&
- <&'user'&>/<&'password'&>
+<&'hostname'&>::<&'port'&>(<&'socket name'&>)[<&'option group'&>]/&&&
+ <&'database'&>/<&'user'&>/<&'password'&>
.endd
-Any of the three sub-parts of the first field can be omitted. For normal use on
+Any of the four sub-parts of the first field can be omitted. For normal use on
the local host it can be left blank or set to just &"localhost"&.
No database need be supplied &-- but if it is absent here, it must be given in
The only character affected by the &%quote_sqlite%& operator is a single
quote, which it doubles.
+.cindex timeout SQLite
+.cindex sqlite "lookup timeout"
The SQLite library handles multiple simultaneous accesses to the database
internally. Multiple readers are permitted, but only one process can
update at once. Attempts to access the database while it is being updated
different types of pattern for each case are described, but first we cover some
general facilities that apply to all four kinds of list.
+Note that other parts of Exim use a &'string list'& which does not
+support all the complexity available in
+domain, host, address and local part lists.
+
.section "Expansion of lists" "SECID75"
list. The effect of each one lasts until the next, or until the end of the
list.
-.new
.section "Mixing wildcarded host names and addresses in host lists" &&&
"SECTmixwilhos"
.cindex "host list" "mixing names and addresses in"
&`+ignore_unknown`&, which was discussed in depth in the first example in
this section.
.endlist
-.wen
.section "Temporary DNS errors when looking up host information" &&&
.cindex "&`+ignore_defer`&"
A temporary DNS lookup failure normally causes a defer action (except when
&%dns_again_means_nonexist%& converts it into a permanent error). However,
-host lists can include &`+ignore_defer`& and &`+include_defer`&, analagous to
+host lists can include &`+ignore_defer`& and &`+include_defer`&, analogous to
&`+ignore_unknown`& and &`+include_unknown`&, as described in the previous
section. These options should be used with care, probably only in non-critical
host lists such as whitelists.
If the ACL returns defer the result is a forced-fail. Otherwise the expansion fails.
+.vitem "&*${certextract{*&<&'field'&>&*}{*&<&'certificate'&>&*}&&&
+ {*&<&'string2'&>&*}{*&<&'string3'&>&*}}*&"
+.cindex "expansion" "extracting cerificate fields"
+.cindex "&%certextract%&" "certificate fields"
+.cindex "certificate" "extracting fields"
+The <&'certificate'&> must be a variable of type certificate.
+The field name is expanded and used to retrieve the relevant field from
+the certificate. Supported fields are:
+.display
+&`version `&
+&`serial_number `&
+&`subject `& RFC4514 DN
+&`issuer `& RFC4514 DN
+&`notbefore `& time
+&`notafter `& time
+&`sig_algorithm `&
+&`signature `&
+&`subj_altname `& tagged list
+&`ocsp_uri `& list
+&`crl_uri `& list
+.endd
+If the field is found,
+<&'string2'&> is expanded, and replaces the whole item;
+otherwise <&'string3'&> is used. During the expansion of <&'string2'&> the
+variable &$value$& contains the value that has been extracted. Afterwards, it
+is restored to any previous value it might have had.
+
+If {<&'string3'&>} is omitted, the item is replaced by an empty string if the
+key is not found. If {<&'string2'&>} is also omitted, the value that was
+extracted is used.
+
+Some field names take optional modifiers, appended and separated by commas.
+
+The field selectors marked as "RFC4514" above
+output a Distinguished Name string which is
+not quite
+parseable by Exim as a comma-separated tagged list
+(the exceptions being elements containing commas).
+RDN elements of a single type may be selected by
+a modifier of the type label; if so the expansion
+result is a list (newline-separated by default).
+The separator may be changed by another modifier of
+a right angle-bracket followed immediately by the new separator.
+Recognised RDN type labels include "CN", "O", "OU" and "DC".
+
+The field selectors marked as "time" above
+take an optional modifier of "int"
+for which the result is the number of seconds since epoch.
+Otherwise the result is a human-readable string
+in the timezone selected by the main "timezone" option.
+
+The field selectors marked as "list" above return a list,
+newline-separated by default,
+(embedded separator characters in elements are doubled).
+The separator may be changed by a modifier of
+a right angle-bracket followed immediately by the new separator.
+
+The field selectors marked as "tagged" above
+prefix each list element with a type string and an equals sign.
+Elements of only one type may be selected by a modifier
+which is one of "dns", "uri" or "mail";
+if so the element tags are omitted.
+
+If not otherwise noted field values are presented in human-readable form.
+
.vitem "&*${dlfunc{*&<&'file'&>&*}{*&<&'function'&>&*}{*&<&'arg'&>&*}&&&
{*&<&'arg'&>&*}...}*&"
.cindex &%dlfunc%&
you need to add &%-shared%& to the gcc command. Also, in the Exim build-time
configuration, you must add &%-export-dynamic%& to EXTRALIBS.
+
+.vitem "&*${env{*&<&'key'&>&*}{*&<&'string1'&>&*}{*&<&'string2'&>&*}}*&"
+.cindex "expansion" "extracting value from environment"
+.cindex "environment" "value from"
+The key is first expanded separately, and leading and trailing white space
+removed.
+This is then searched for as a name in the environment.
+If a variable is found then its value is placed in &$value$&
+and <&'string1'&> is expanded, otherwise <&'string2'&> is expanded.
+
+Instead of {<&'string2'&>} the word &"fail"& (not in curly brackets) can
+appear, for example:
+.code
+${env{USER}{$value} fail }
+.endd
+This forces an expansion failure (see section &<<SECTforexpfai>>&);
+{<&'string1'&>} must be present for &"fail"& to be recognized.
+
+If {<&'string2'&>} is omitted an empty string is substituted on
+search failure.
+If {<&'string1'&>} is omitted the search result is substituted on
+search success.
+
+
.vitem "&*${extract{*&<&'key'&>&*}{*&<&'string1'&>&*}{*&<&'string2'&>&*}&&&
{*&<&'string3'&>&*}}*&"
.cindex "expansion" "extracting substrings by key"
Upper case and lower case letters are synonymous in header names. If the
following character is white space, the terminating colon may be omitted, but
this is not recommended, because you may then forget it when it is needed. When
-white space terminates the header name, it is included in the expanded string.
-If the message does not contain the given header, the expansion item is
-replaced by an empty string. (See the &%def%& condition in section
-&<<SECTexpcond>>& for a means of testing for the existence of a header.)
+white space terminates the header name, this white space is included in the
+expanded string. If the message does not contain the given header, the
+expansion item is replaced by an empty string. (See the &%def%& condition in
+section &<<SECTexpcond>>& for a means of testing for the existence of a
+header.)
If there is more than one header with the same name, they are all concatenated
to form the substitution string, up to a maximum length of 64K. Unless
condition = ${if >{$acl_m4}{3}}
.endd
+
+
+.new
+.vitem &*${imapfolder{*&<&'foldername'&>&*}}*&
+.cindex expansion "imap folder"
+.cindex "&%imapfolder%& expansion item"
+This item converts a (possibly multilevel, or with non-ASCII characters)
+folder specification to a Maildir name for filesystem use.
+For information on internationalisation support see &<<SECTi18nMDA>>&.
+.wen
+
+
+
.vitem &*${length{*&<&'string1'&>&*}{*&<&'string2'&>&*}}*&
.cindex "expansion" "string truncation"
.cindex "&%length%& expansion item"
.code
${listextract{-3}{<, x,42,99,& Mailer,,/bin/bash}{result: $value}}
.endd
-yields &"result: 99"&.
+yields &"result: 42"&.
If {<&'string3'&>} is omitted, an empty string is used for string3.
If {<&'string2'&>} is also omitted, the value that was
.cindex "expansion" "inserting from a socket"
.cindex "socket, use of in expansion"
.cindex "&%readsocket%& expansion item"
-This item inserts data from a Unix domain or Internet socket into the expanded
+This item inserts data from a Unix domain or TCP socket into the expanded
string. The minimal way of using it uses just two arguments, as in these
examples:
.code
{*&<&'string2'&>&*}}*&"
.cindex "expansion" "running a command"
.cindex "&%run%& expansion item"
-The command and its arguments are first expanded separately, and then the
-command is run in a separate process, but under the same uid and gid. As in
-other command executions from Exim, a shell is not used by default. If you want
+The command and its arguments are first expanded as one string. The string is
+split apart into individual arguments by spaces, and then the command is run
+in a separate process, but under the same uid and gid. As in other command
+executions from Exim, a shell is not used by default. If the command requires
a shell, you must explicitly code it.
+Since the arguments are split by spaces, when there is a variable expansion
+which has an empty result, it will cause the situation that the argument will
+simply be omitted when the program is actually executed by Exim. If the
+script/program requires a specific number of arguments and the expanded
+variable could possibly result in this empty expansion, the variable must be
+quoted. This is more difficult if the expanded variable itself could result
+in a string containing quotes, because it would interfere with the quotes
+around the command arguments. A possible guard against this is to wrap the
+variable in the &%sg%& operator to change any quote marks to some other
+character.
+
The standard input for the command exists, but is empty. The standard output
and standard error are set to the same file descriptor.
.cindex "return code" "from &%run%& expansion"
+.vitem &*${sort{*&<&'string'&>&*}{*&<&'comparator'&>&*}{*&<&'extractor'&>&*}}*&
+.cindex sorting "a list"
+.cindex list sorting
+.cindex expansion "list sorting"
+After expansion, <&'string'&> is interpreted as a list, colon-separated by
+default, but the separator can be changed in the usual way.
+The <&'comparator'&> argument is interpreted as the operator
+of a two-argument expansion condition.
+The numeric operators plus ge, gt, le, lt (and ~i variants) are supported.
+The comparison should return true when applied to two values
+if the first value should sort before the second value.
+The <&'extractor'&> expansion is applied repeatedly to elements of the list,
+the element being placed in &$item$&,
+to give values for comparison.
+
+The item result is a sorted list,
+with the original list separator,
+of the list elements (in full) of the original.
+
+Examples:
+.code
+${sort{3:2:1:4}{<}{$item}}
+.endd
+sorts a list of numbers, and
+.code
+${sort {${lookup dnsdb{>:,,mx=example.com}}} {<} {${listextract{1}{<,$item}}}}
+.endd
+will sort an MX lookup into priority order.
+
+
.vitem &*${substr{*&<&'string1'&>&*}{*&<&'string2'&>&*}{*&<&'string3'&>&*}}*&
.cindex "&%substr%& expansion item"
.cindex "substring extraction"
To clarify "list of addresses in RFC 2822 format" mentioned above, Exim follows
a strict interpretation of header line formatting. Exim parses the bare,
unquoted portion of an email address and if it finds a comma, treats it as an
-email address seperator. For the example header line:
+email address separator. For the example header line:
.code
From: =?iso-8859-2?Q?Last=2C_First?= <user@example.com>
.endd
byte value 127 is converted to &`\x7f`&.
+.new
+.vitem &*${ipv6denorm:*&<&'string'&>&*}*&
+.cindex "&%ipv6denorm%& expansion item"
+.cindex "IP address" normalisation
+This expands an IPv6 address to a full eight-element colon-separated set
+of hex digits including leading zeroes.
+A trailing ipv4-style dotted-decimal set is converted to hex.
+Pure IPv4 addresses are converted to IPv4-mapped IPv6.
+
+.vitem &*${ipv6norm:*&<&'string'&>&*}*&
+.cindex "&%ipv6norm%& expansion item"
+.cindex "IP address" normalisation
+.cindex "IP address" "canonical form"
+This converts an IPv6 address to canonical form.
+Leading zeroes of groups are omitted, and the longest
+set of zero-valued groups is replaced with a double colon.
+A trailing ipv4-style dotted-decimal set is converted to hex.
+Pure IPv4 addresses are converted to IPv4-mapped IPv6.
+.wen
+
+
.vitem &*${lc:*&<&'string'&>&*}*&
.cindex "case forcing in strings"
.cindex "string" "case forcing"
.vitem &*${md5:*&<&'string'&>&*}*&
.cindex "MD5 hash"
.cindex "expansion" "MD5 hash"
+.cindex "certificate fingerprint"
.cindex "&%md5%& expansion item"
The &%md5%& operator computes the MD5 hash value of the string, and returns it
as a 32-digit hexadecimal number, in which any letters are in lower case.
.vitem &*${reverse_ip:*&<&'ipaddr'&>&*}*&
.cindex "expansion" "IP address"
This operator reverses an IP address; for IPv4 addresses, the result is in
-dotted-quad decimal form, while for IPv6 addreses the result is in
+dotted-quad decimal form, while for IPv6 addresses the result is in
dotted-nibble hexadecimal form. In both cases, this is the "natural" form
for DNS. For example,
.code
This operator encodes text according to the rules of RFC 2047. This is an
encoding that is used in header lines to encode non-ASCII characters. It is
assumed that the input string is in the encoding specified by the
-&%headers_charset%& option, which defaults to ISO-8859-1. If the string
+&%headers_charset%& option, which gets its default at build time. If the string
contains only characters in the range 33&--126, and no instances of the
characters
.code
.vitem &*${sha1:*&<&'string'&>&*}*&
.cindex "SHA-1 hash"
.cindex "expansion" "SHA-1 hashing"
+.cindex "certificate fingerprint"
.cindex "&%sha2%& expansion item"
The &%sha1%& operator computes the SHA-1 hash value of the string, and returns
it as a 40-digit hexadecimal number, in which any letters are in upper case.
+.vitem &*${sha256:*&<&'certificate'&>&*}*&
+.cindex "SHA-256 hash"
+.cindex "certificate fingerprint"
+.cindex "expansion" "SHA-256 hashing"
+.cindex "&%sha256%& expansion item"
+The &%sha256%& operator computes the SHA-256 hash fingerprint of the
+certificate,
+and returns
+it as a 64-digit hexadecimal number, in which any letters are in upper case.
+Only arguments which are a single variable of certificate type are supported.
+
+
.vitem &*${stat:*&<&'string'&>&*}*&
.cindex "expansion" "statting a file"
.cindex "file" "extracting characteristics"
.cindex "expansion" "utf-8 forcing"
.cindex "&%utf8clean%& expansion item"
This replaces any invalid utf-8 sequence in the string by the character &`?`&.
+
+.new
+.vitem "&*${utf8_domain_to_alabel:*&<&'string'&>&*}*&" &&&
+ "&*${utf8_domain_from_alabel:*&<&'string'&>&*}*&" &&&
+ "&*${utf8_localpart_to_alabel:*&<&'string'&>&*}*&" &&&
+ "&*${utf8_localpart_from_alabel:*&<&'string'&>&*}*&"
+.cindex expansion UTF-8
+.cindex UTF-8 expansion
+.cindex EAI
+.cindex internationalisation
+.cindex "&%utf8_domain_to_alabel%& expansion item"
+.cindex "&%utf8_domain_from_alabel%& expansion item"
+.cindex "&%utf8_localpart_to_alabel%& expansion item"
+.cindex "&%utf8_localpart_from_alabel%& expansion item"
+These convert EAI mail name components between UTF-8 and a-label forms.
+For information on internationalisation support see &<<SECTi18nMTA>>&.
+.wen
.endlist
When a &%match%& expansion condition succeeds, these variables contain the
captured substrings identified by the regular expression during subsequent
processing of the success string of the containing &%if%& expansion item.
-However, they do not retain their values afterwards; in fact, their previous
+In the expansion condition case
+they do not retain their values afterwards; in fact, their previous
values are restored at the end of processing an &%if%& item. The numerical
variables may also be set externally by some other matching process which
precedes the expansion of the string. For example, the commands available in
Exim filter files include an &%if%& command with its own regular expression
matching condition.
+.vitem "&$acl_arg1$&, &$acl_arg2$&, etc"
+Within an acl condition, expansion condition or expansion item
+any arguments are copied to these variables,
+any unused variables being made empty.
+
.vitem "&$acl_c...$&"
Values can be placed in these variables by the &%set%& modifier in an ACL. They
can be given any name that starts with &$acl_c$& and is at least six characters
and can be accessed by filters, routers, and transports during subsequent
delivery.
+.vitem &$acl_narg$&
+Within an acl condition, expansion condition or expansion item
+this variable has the number of arguments.
+
.vitem &$acl_verify_message$&
.vindex "&$acl_verify_message$&"
After an address verification has failed, this variable contains the failure
&$originator_uid$&). If Exim re-execs itself, this variable in the new
incarnation normally contains the Exim uid.
-.vitem &$compile_date$&
-.vindex "&$compile_date$&"
-The date on which the Exim binary was compiled.
+.vitem &$callout_address$&
+.vindex "&$callout_address$&"
+After a callout for verification, spamd or malware daemon service, the
+address that was connected to.
.vitem &$compile_number$&
.vindex "&$compile_number$&"
of times it has been compiled. This serves to distinguish different
compilations of the same version of the program.
+.vitem &$config_dir$&
+.vindex "&$config_dir$&"
+The directory name of the main configuration file. That is, the content of
+&$config_file$& with the last component stripped. The value does not
+contain the trailing slash. If &$config_file$& does not contain a slash,
+&$config_dir$& is ".".
+
+.vitem &$config_file$&
+.vindex "&$config_file$&"
+The name of the main configuration file Exim is using.
+
.vitem &$demime_errorlevel$&
.vindex "&$demime_errorlevel$&"
This variable is available when Exim is compiled with
content-scanning extension and the obsolete &%demime%& condition. For details,
see section &<<SECTdemimecond>>&.
+.vitem &$dkim_cur_signer$& &&&
+ &$dkim_verify_status$& &&&
+ &$dkim_verify_reason$& &&&
+ &$dkim_domain$& &&&
+ &$dkim_identity$& &&&
+ &$dkim_selector$& &&&
+ &$dkim_algo$& &&&
+ &$dkim_canon_body$& &&&
+ &$dkim_canon_headers$& &&&
+ &$dkim_copiedheaders$& &&&
+ &$dkim_bodylength$& &&&
+ &$dkim_created$& &&&
+ &$dkim_expires$& &&&
+ &$dkim_headernames$& &&&
+ &$dkim_key_testing$& &&&
+ &$dkim_key_nosubdomains$& &&&
+ &$dkim_key_srvtype$& &&&
+ &$dkim_key_granularity$& &&&
+ &$dkim_key_notes$& &&&
+ &$dkim_key_length$&
+These variables are only available within the DKIM ACL.
+For details see chapter &<<CHAPdkim>>&.
+
+.vitem &$dkim_signers$&
+.vindex &$dkim_signers$&
+When a message has been received this variable contains
+a colon-separated list of signer domains and identities for the message.
+For details see chapter &<<CHAPdkim>>&.
+
.vitem &$dnslist_domain$& &&&
&$dnslist_matched$& &&&
&$dnslist_text$& &&&
.vindex "&$exim_uid$&"
This variable contains the numerical value of the Exim user id.
+.vitem &$exim_version$&
+.vindex "&$exim_version$&"
+This variable contains the version string of the Exim build.
+The first character is a major version number, currently 4.
+Then after a dot, the next group of digits is a minor version number.
+There may be other characters following the minor version.
+
.vitem &$found_extension$&
.vindex "&$found_extension$&"
This variable is available when Exim is compiled with the
.vindex "&$host_lookup_failed$&"
See &$host_lookup_deferred$&.
+.vitem &$host_port$&
+.vindex "&$host_port$&"
+This variable is set to the remote host's TCP port whenever &$host$& is set
+for an outbound connection.
+
.vitem &$inode$&
.vindex "&$inode$&"
the space value is -1. See also the &%check_log_space%& option.
+.vitem &$lookup_dnssec_authenticated$&
+.vindex "&$lookup_dnssec_authenticated$&"
+This variable is set after a DNS lookup done by
+a dnsdb lookup expansion, dnslookup router or smtp transport.
+.cindex "DNS" "DNSSEC"
+It will be empty if &(DNSSEC)& was not requested,
+&"no"& if the result was not labelled as authenticated data
+and &"yes"& if it was.
+Results that are labelled as authoritative answer that match
+the &%dns_trust_aa%& configuration variable count also
+as authenticated data.
+
.vitem &$mailstore_basename$&
.vindex "&$mailstore_basename$&"
This variable is set only when doing deliveries in &"mailstore"& format in the
contents of header lines is done.
.vitem &$message_id$&
-This is an old name for &$message_exim_id$&, which is now deprecated.
+This is an old name for &$message_exim_id$&. It is now deprecated.
.vitem &$message_linecount$&
.vindex "&$message_linecount$&"
qualified host name. See also &$smtp_active_hostname$&.
+.new
+.vitem &$proxy_host_address$& &&&
+ &$proxy_host_port$& &&&
+ &$proxy_target_address$& &&&
+ &$proxy_target_port$& &&&
+ &$proxy_session$&
+These variables are only available when built with Proxy Protocol
+or Socks5 support
+For details see chapter &<<SECTproxyInbound>>&.
+.wen
+
+.new
+.vitem &$prdr_requested$&
+.cindex "PRDR" "variable for"
+This variable is set to &"yes"& if PRDR was requested by the client for the
+current message, otherwise &"no"&.
+.wen
+
.vitem &$prvscheck_address$&
This variable is used in conjunction with the &%prvscheck%& expansion item,
which is described in sections &<<SECTexpansionitems>>& and
values of &$received_ip_address$& and &$received_port$& are saved with any
messages that are received, thus making these variables available at delivery
time.
-
-&*Note:*& There are no equivalent variables for outgoing connections, because
-the values are unknown (unless they are explicitly set by options of the
-&(smtp)& transport).
+For outbound connections see &$sending_ip_address$&.
.vitem &$received_port$&
.vindex "&$received_port$&"
This variable is set to contain the matching regular expression after a
&%regex%& ACL condition has matched (see section &<<SECTscanregex>>&).
+.vitem "&$regex1$&, &$regex2$&, etc"
+.cindex "regex submatch variables (&$1regex$& &$2regex$& etc)"
+When a &%regex%& or &%mime_regex%& ACL condition succeeds,
+these variables contain the
+captured substrings identified by the regular expression.
+
.vitem &$reply_address$&
.vindex "&$reply_address$&"
the argument of a HELO or EHLO command. This is omitted if it is identical to
the verified host name or to the host's IP address in square brackets.
+.vitem &$sender_helo_dnssec$&
+.vindex "&$sender_helo_dnssec$&"
+This boolean variable is true if a successful HELO verification was
+.cindex "DNS" "DNSSEC"
+done using DNS information the resolver library stated was authenticated data.
+
.vitem &$sender_helo_name$&
.vindex "&$sender_helo_name$&"
When a message is received from a remote host that has issued a HELO or EHLO
.vitem &$sender_host_address$&
.vindex "&$sender_host_address$&"
-When a message is received from a remote host, this variable contains that
-host's IP address. For locally submitted messages, it is empty.
+When a message is received from a remote host using SMTP,
+this variable contains that
+host's IP address. For locally non-SMTP submitted messages, it is empty.
.vitem &$sender_host_authenticated$&
.vindex "&$sender_host_authenticated$&"
.vitem &$sender_host_dnssec$&
.vindex "&$sender_host_dnssec$&"
-If &$sender_host_name$& has been populated (by reference, &%hosts_lookup%& or
+If an attempt to populate &$sender_host_name$& has been made
+(by reference, &%hosts_lookup%& or
otherwise) then this boolean will have been set true if, and only if, the
-resolver library states that the reverse DNS was authenticated data. At all
+resolver library states that both
+the reverse and forward DNS were authenticated data. At all
other times, this variable is false.
+.cindex "DNS" "DNSSEC"
It is likely that you will need to coerce DNSSEC support on in the resolver
library, by setting:
.code
.endd
Exim does not perform DNSSEC validation itself, instead leaving that to a
-validating resolver (eg, unbound, or bind with suitable configuration).
-
-Exim does not (currently) check to see if the forward DNS was also secured
-with DNSSEC, only the reverse DNS.
+validating resolver (e.g. unbound, or bind with suitable configuration).
If you have changed &%host_lookup_order%& so that &`bydns`& is not the first
mechanism in the list, then this variable will be false.
this depends upon the TLS implementation used.
If TLS has not been negotiated, the value will be 0.
+.vitem &$tls_in_ourcert$&
+.vindex "&$tls_in_ourcert$&"
+This variable refers to the certificate presented to the peer of an
+inbound connection when the message was received.
+It is only useful as the argument of a
+&%certextract%& expansion item, &%md5%&, &%sha1%& or &%sha256%& operator,
+or a &%def%& condition.
+
+.vitem &$tls_in_peercert$&
+.vindex "&$tls_in_peercert$&"
+This variable refers to the certificate presented by the peer of an
+inbound connection when the message was received.
+It is only useful as the argument of a
+&%certextract%& expansion item, &%md5%&, &%sha1%& or &%sha256%& operator,
+or a &%def%& condition.
+If certificate verification fails it may refer to a failing chain element
+which is not the leaf.
+
+.vitem &$tls_out_ourcert$&
+.vindex "&$tls_out_ourcert$&"
+This variable refers to the certificate presented to the peer of an
+outbound connection. It is only useful as the argument of a
+&%certextract%& expansion item, &%md5%&, &%sha1%& or &%sha256%& operator,
+or a &%def%& condition.
+
+.vitem &$tls_out_peercert$&
+.vindex "&$tls_out_peercert$&"
+This variable refers to the certificate presented by the peer of an
+outbound connection. It is only useful as the argument of a
+&%certextract%& expansion item, &%md5%&, &%sha1%& or &%sha256%& operator,
+or a &%def%& condition.
+If certificate verification fails it may refer to a failing chain element
+which is not the leaf.
+
.vitem &$tls_in_certificate_verified$&
.vindex "&$tls_in_certificate_verified$&"
This variable is set to &"1"& if a TLS certificate was verified when the
message was received, and &"0"& otherwise.
-The deprecated &$tls_certificate_verfied$& variable refers to the inbound side
+The deprecated &$tls_certificate_verified$& variable refers to the inbound side
except when used in the context of an outbound SMTP delivery, when it refers to
the outbound.
&<<CHAPTLS>>& for details of TLS support and chapter &<<CHAPsmtptrans>>& for
details of the &(smtp)& transport.
+.vitem &$tls_in_ocsp$&
+.vindex "&$tls_in_ocsp$&"
+When a message is received from a remote client connection
+the result of any OCSP request from the client is encoded in this variable:
+.code
+0 OCSP proof was not requested (default value)
+1 No response to request
+2 Response not verified
+3 Verification failed
+4 Verification succeeded
+.endd
+
+.vitem &$tls_out_ocsp$&
+.vindex "&$tls_out_ocsp$&"
+When a message is sent to a remote host connection
+the result of any OCSP request made is encoded in this variable.
+See &$tls_in_ocsp$& for values.
+
.vitem &$tls_in_peerdn$&
.vindex "&$tls_in_peerdn$&"
.vindex "&$tls_peerdn$&"
connection, and Exim is configured to request a certificate from the client,
the value of the Distinguished Name of the certificate is made available in the
&$tls_in_peerdn$& during subsequent processing.
+If certificate verification fails it may refer to a failing chain element
+which is not the leaf.
The deprecated &$tls_peerdn$& variable refers to the inbound side
except when used in the context of an outbound SMTP delivery, when it refers to
connection, and Exim is configured to request a certificate from the server,
the value of the Distinguished Name of the certificate is made available in the
&$tls_out_peerdn$& during subsequent processing.
+If certificate verification fails it may refer to a failing chain element
+which is not the leaf.
.vitem &$tls_in_sni$&
.vindex "&$tls_in_sni$&"
or external command, as described above. It is also used during a
&*reduce*& expansion.
+.vitem &$verify_mode$&
+.vindex "&$verify_mode$&"
+While a router or transport is being run in verify mode
+or for cutthrough delivery,
+contains "S" for sender-verification or "R" for recipient-verification.
+Otherwise, empty.
+
.vitem &$version_number$&
.vindex "&$version_number$&"
The version number of Exim.
following options:
.ilist
-&%daemon_smtp_ports%& contains a list of default ports. (For backward
-compatibility, this option can also be specified in the singular.)
+&%daemon_smtp_ports%& contains a list of default ports
+or service names.
+(For backward compatibility, this option can also be specified in the singular.)
.next
&%local_interfaces%& contains list of interface IP addresses on which to
listen. Each item may optionally also specify a port.
Exim supports the obsolete SSMTP protocol (also known as SMTPS) that was used
before the STARTTLS command was standardized for SMTP. Some legacy clients
still use this protocol. If the &%tls_on_connect_ports%& option is set to a
-list of port numbers, connections to those ports must use SSMTP. The most
+list of port numbers or service names,
+connections to those ports must use SSMTP. The most
common use of this option is expected to be
.code
tls_on_connect_ports = 465
.row &%message_logs%& "create per-message logs"
.row &%preserve_message_logs%& "after message completion"
.row &%process_log_path%& "for SIGUSR1 and &'exiwhat'&"
+.row &%slow_lookup_log%& "control logging of slow DNS lookups"
.row &%syslog_duplication%& "controls duplicate log lines on syslog"
.row &%syslog_facility%& "set syslog &""facility""& field"
.row &%syslog_processname%& "set syslog &""ident""& field"
.row &%acl_smtp_auth%& "ACL for AUTH"
.row &%acl_smtp_connect%& "ACL for connection"
.row &%acl_smtp_data%& "ACL for DATA"
+.row &%acl_smtp_data_prdr%& "ACL for DATA, per-recipient"
.row &%acl_smtp_dkim%& "ACL for DKIM verification"
.row &%acl_smtp_etrn%& "ACL for ETRN"
.row &%acl_smtp_expn%& "ACL for EXPN"
.row &%acl_smtp_mail%& "ACL for MAIL"
.row &%acl_smtp_mailauth%& "ACL for AUTH on MAIL command"
.row &%acl_smtp_mime%& "ACL for MIME parts"
+.row &%acl_smtp_notquit%& "ACL for non-QUIT terminations"
.row &%acl_smtp_predata%& "ACL for start of data"
.row &%acl_smtp_quit%& "ACL for QUIT"
.row &%acl_smtp_rcpt%& "ACL for RCPT"
.row &%helo_verify_hosts%& "HELO hard-checked for these hosts"
.row &%host_lookup%& "host name looked up for these hosts"
.row &%host_lookup_order%& "order of DNS and local name lookups"
+.row &%hosts_proxy%& "use proxy protocol for these hosts"
.row &%host_reject_connection%& "reject connection from these hosts"
.row &%hosts_treat_as_local%& "useful in some cluster configurations"
.row &%local_scan_timeout%& "timeout for &[local_scan()]&"
.row &%tls_crl%& "certificate revocation list"
.row &%tls_dh_max_bits%& "clamp D-H bit count suggestion"
.row &%tls_dhparam%& "DH parameters for server"
+.row &%tls_eccurve%& "EC curve selection for server"
+.row &%tls_ocsp_file%& "location of server certificate status proof"
.row &%tls_on_connect_ports%& "specify SSMTP (SMTPS) ports"
.row &%tls_privatekey%& "location of server private key"
.row &%tls_remember_esmtp%& "don't reset after starting TLS"
See also the &'Policy controls'& section above.
.table2
+.row &%dkim_verify_signers%& "DKIM domain for which DKIM ACL is run"
.row &%host_lookup%& "host name looked up for these hosts"
.row &%host_lookup_order%& "order of DNS and local name lookups"
.row &%recipient_unqualified_hosts%& "may send unqualified recipients"
.table2
.row &%accept_8bitmime%& "advertise 8BITMIME"
.row &%auth_advertise_hosts%& "advertise AUTH to these hosts"
+.row &%dsn_advertise_hosts%& "advertise DSN extensions to these hosts"
.row &%ignore_fromline_hosts%& "allow &""From ""& from these hosts"
.row &%ignore_fromline_local%& "allow &""From ""& from local SMTP"
.row &%pipelining_advertise_hosts%& "advertise pipelining to these hosts"
+.row &%prdr_enable%& "advertise PRDR to all hosts"
+.row &%smtputf8_advertise_hosts%& "advertise SMTPUTF8 to these hosts"
.row &%tls_advertise_hosts%& "advertise TLS to these hosts"
.endtable
.row &%dns_ipv4_lookup%& "only v4 lookup for these domains"
.row &%dns_retrans%& "parameter for resolver"
.row &%dns_retry%& "parameter for resolver"
+.row &%dns_trust_aa%& "DNS zones trusted as authentic"
.row &%dns_use_edns0%& "parameter for resolver"
.row &%hold_domains%& "hold delivery for these domains"
.row &%local_interfaces%& "for routing checks"
processed and the message itself has been received, but before the final
acknowledgment is sent. See chapter &<<CHAPACL>>& for further details.
+.option acl_smtp_data_prdr main string&!! accept
+.cindex "PRDR" "ACL for"
+.cindex "DATA" "PRDR ACL for"
+.cindex "&ACL;" "PRDR-related"
+.cindex "&ACL;" "per-user data processing"
+This option defines the ACL that,
+if the PRDR feature has been negotiated,
+is run for each recipient after an SMTP DATA command has been
+processed and the message itself has been received, but before the
+acknowledgment is sent. See chapter &<<CHAPACL>>& for further details.
+
+.option acl_smtp_dkim main string&!! unset
+.cindex DKIM "ACL for"
+This option defines the ACL that is run for each DKIM signature
+of a received message.
+See chapter &<<CHAPdkim>>& for further details.
+
.option acl_smtp_etrn main string&!! unset
.cindex "ETRN" "ACL for"
This option defines the ACL that is run when an SMTP ETRN command is
extension. It defines the ACL that is run for each MIME part in a message. See
section &<<SECTscanmimepart>>& for details.
+.option acl_smtp_notquit main string&!! unset
+.cindex "not-QUIT, ACL for"
+This option defines the ACL that is run when an SMTP session
+ends without a QUIT command being received.
+See chapter &<<CHAPACL>>& for further details.
+
.option acl_smtp_predata main string&!! unset
This option defines the ACL that is run when an SMTP DATA command is
received, before the message itself is received. See chapter &<<CHAPACL>>& for
It appears that more and more DNS zone administrators are breaking the rules
and putting domain names that look like IP addresses on the right hand side of
MX records. Exim follows the rules and rejects this, giving an error message
-that explains the mis-configuration. However, some other MTAs support this
+that explains the misconfiguration. However, some other MTAs support this
practice, so to avoid &"Why can't Exim do this?"& complaints,
&%allow_mx_to_ip%& exists, in order to enable this heinous activity. It is not
recommended, except when you have no other choice.
to handle IPv6 literal addresses.
+.option dkim_verify_signers main "domain list&!!" $dkim_signers
+.cindex DKIM "controlling calls to the ACL"
+This option gives a list of DKIM domains for which the DKIM ACL is run.
+It is expanded after the message is received; by default it runs
+the ACL once for each signature in the message.
+See chapter &<<CHAPdkim>>&.
+
+
.option dns_again_means_nonexist main "domain list&!!" unset
.cindex "DNS" "&""try again""& response; overriding"
DNS lookups give a &"try again"& response for the DNS errors
.option dns_retrans main time 0s
.cindex "DNS" "resolver options"
+.cindex timeout "dns lookup"
+.cindex "DNS" timeout
The options &%dns_retrans%& and &%dns_retry%& can be used to set the
retransmission and retry parameters for DNS lookups. Values of zero (the
defaults) leave the system default settings unchanged. The first value is the
parameter values are available in the external resolver interface structure,
but nowhere does it seem to describe how they are used or what you might want
to set in them.
+See also the &%slow_lookup_log%& option.
.option dns_retry main integer 0
See &%dns_retrans%& above.
+.option dns_trust_aa main "domain list&!!" unset
+.cindex "DNS" "resolver options"
+.cindex "DNS" "DNSSEC"
+If this option is set then lookup results marked with the AA bit
+(Authoritative Answer) are trusted the same way as if they were
+DNSSEC-verified. The authority section's name of the answer must
+match with this expanded domain list.
+
+Use this option only if you talk directly to a resolver that is
+authoritative for some zones and does not set the AD (Authentic Data)
+bit in the answer. Some DNS servers may have an configuration option to
+mark the answers from their own zones as verified (they set the AD bit).
+Others do not have this option. It is considered as poor practice using
+a resolver that is an authoritative server for some zones.
+
+Use this option only if you really have to (e.g. if you want
+to use DANE for remote delivery to a server that is listed in the DNS
+zones that your resolver is authoritative for).
+
+If the DNS answer packet has the AA bit set and contains resource record
+in the answer section, the name of the first NS record appearing in the
+authority section is compared against the list. If the answer packet is
+authoritative but the answer section is empty, the name of the first SOA
+record in the authoritative section is used instead.
+
+.cindex "DNS" "resolver options"
.option dns_use_edns0 main integer -1
.cindex "DNS" "resolver options"
.cindex "DNS" "EDNS0"
handled CR and LF characters in incoming messages. What happens now is
described in section &<<SECTlineendings>>&.
+.option dsn_advertise_hosts main "host list&!!" unset
+.cindex "bounce messages" "success"
+.cindex "DSN" "success"
+.cindex "Delivery Status Notification" "success"
+DSN extensions (RFC3461) will be advertised in the EHLO message to,
+and accepted from, these hosts.
+Hosts may use the NOTIFY and ENVID options on RCPT TO commands,
+and RET and ORCPT options on MAIL FROM commands.
+A NOTIFY=SUCCESS option requests success-DSN messages.
+A NOTIFY= option with no argument requests that no delay or failure DSNs
+are sent.
+
.option dsn_from main "string&!!" "see below"
.cindex "&'From:'& header line" "in bounces"
.cindex "bounce messages" "&'From:'& line, specifying"
Exim's transports have an option for adding an &'Envelope-to:'& header to a
message when it is delivered, in exactly the same way as &'Return-path:'& is
handled. &'Envelope-to:'& records the original recipient address from the
-messages's envelope that caused the delivery to happen. Such headers should not
+message's envelope that caused the delivery to happen. Such headers should not
be present in incoming messages, and this option causes them to be removed at
the time the message is received, to avoid any problems that might occur when a
delivered message is subsequently sent on to some other recipient.
. Allow this long option name to split; give it unsplit as a fifth argument
. for the automatic .oindex that is generated by .option.
-.option "extract_addresses_remove_ &~&~arguments" main boolean true &&&
+.option "extract_addresses_remove_arguments" main boolean true &&&
extract_addresses_remove_arguments
.oindex "&%-t%&"
.cindex "command line" "addresses with &%-t%&"
matches the host name that Exim obtains by doing a reverse lookup of the
calling host address, or
.next
-when looked up using &[gethostbyname()]& (or &[getipnodebyname()]& when
-available) yields the calling host address.
+when looked up in DNS yields the calling host address.
.endlist
However, the EHLO or HELO command is not rejected if any of the checks
fail. Processing continues, but the result of the check is remembered, and can
be detected later in an ACL by the &`verify = helo`& condition.
+If DNS was used for successful verification, the variable
+.cindex "DNS" "DNSSEC"
+&$helo_verify_dnssec$& records the DNSSEC status of the lookups.
+
.option helo_verify_hosts main "host list&!!" unset
.cindex "HELO verifying" "mandatory"
.cindex "EHLO" "verifying, mandatory"
+.new
+.option hosts_proxy main "host list&!!" unset
+.cindex proxy "proxy protocol"
+This option enables use of Proxy Protocol proxies for incoming
+connections. For details see &<<SECTproxyInbound>>&.
+.wen
+
+
.option hosts_treat_as_local main "domain list&!!" unset
.cindex "local host" "domains treated as"
.cindex "host" "treated as local"
This option sets the path which is used to determine the names of Exim's log
files, or indicates that logging is to be to syslog, or both. It is expanded
when Exim is entered, so it can, for example, contain a reference to the host
-name. If no specific path is set for the log files at compile or run time, they
-are written in a sub-directory called &_log_& in Exim's spool directory.
+name. If no specific path is set for the log files at compile or run time,
+or if the option is unset at run time (i.e. &`log_file_path = `&)
+they are written in a sub-directory called &_log_& in Exim's spool directory.
Chapter &<<CHAPlog>>& contains further details about Exim's logging, and
section &<<SECTwhelogwri>>& describes how the contents of &%log_file_path%& are
used. If this string is fixed at your installation (contains no expansion
maximum size that your virus-scanner is configured to support, you may get
failures triggered by large mails. The right size to configure for the
virus-scanner depends upon what data is passed and the options in use but it's
-probably safest to just set it to a little larger than this value. Eg, with a
+probably safest to just set it to a little larger than this value. E.g., with a
default Exim message size of 50M and a default ClamAV StreamMaxLength of 10M,
some problems may result.
adjusted lightly. An unrecognised item will be detected at startup, by
invoking Exim with the &%-bV%& flag.
+The option affects Exim operating both as a server and as a client.
+
Historical note: prior to release 4.80, Exim defaulted this value to
"+dont_insert_empty_fragments", which may still be needed for compatibility
with some clients, but which lowers security by increasing exposure to
some now infamous attacks.
-An example:
+Examples:
.code
# Make both old MS and old Eudora happy:
openssl_options = -all +microsoft_big_sslv3_buffer \
+dont_insert_empty_fragments
+
+# Disable older protocol versions:
+openssl_options = +no_sslv2 +no_sslv3
.endd
Possible options may include:
not count as protocol errors (see &%smtp_max_synprot_errors%&).
+.option prdr_enable main boolean false
+.cindex "PRDR" "enabling on server"
+This option can be used to enable the Per-Recipient Data Response extension
+to SMTP, defined by Eric Hall.
+If the option is set, PRDR is advertised by Exim when operating as a server.
+If the client requests PRDR, and more than one recipient, for a message
+an additional ACL is called for each recipient after the message content
+is received. See section &<<SECTPRDRACL>>&.
+
.option preserve_message_logs main boolean false
.cindex "message logs" "preserving"
If this option is set, message log files are not deleted when messages are
This option is an obsolete synonym for &%bounce_return_size_limit%&.
-.option rfc1413_hosts main "host list&!!" *
+.option rfc1413_hosts main "host list&!!" @[]
.cindex "RFC 1413"
.cindex "host" "for RFC 1413 calls"
-RFC 1413 identification calls are made to any client host which matches an item
-in the list.
+RFC 1413 identification calls are made to any client host which matches
+an item in the list.
+The default value specifies just this host, being any local interface
+for the system.
-.option rfc1413_query_timeout main time 5s
+.option rfc1413_query_timeout main time 0s
.cindex "RFC 1413" "query timeout"
.cindex "timeout" "for RFC 1413 call"
This sets the timeout on RFC 1413 identification calls. If it is set to zero,
using TCP/IP), and the &%-bnq%& option was not set.
+.option slow_lookup_log main integer 0
+.cindex "logging" "slow lookups"
+.cindex "dns" "logging slow lookups"
+This option controls logging of slow lookups.
+If the value is nonzero it is taken as a number of milliseconds
+and lookups taking longer than this are logged.
+Currently this applies only to DNS lookups.
+
+
+
.option smtp_accept_keepalive main boolean true
.cindex "keepalive" "on incoming connection"
This option controls the setting of the SO_KEEPALIVE option on incoming
See &%smtp_ratelimit_hosts%& above.
-.option smtp_receive_timeout main time 5m
+.option smtp_receive_timeout main time&!! 5m
.cindex "timeout" "for SMTP input"
.cindex "SMTP" "input timeout"
This sets a timeout value for SMTP reception. It applies to all forms of SMTP
The former means that Exim was expecting to read an SMTP command; the latter
means that it was in the DATA phase, reading the contents of a message.
+If the first character of the option is a &"$"& the option is
+expanded before use and may depend on
+&$sender_host_name$&, &$sender_host_address$& and &$sender_host_port$&.
+
.oindex "&%-os%&"
The value set by this option can be overridden by the
550 failing address in "From" header is: <user@dom.ain
.endd
+
+.new
+.option smtputf8_advertise_hosts main "host list&!!" *
+.cindex "SMTPUTF8" "advertising"
+When Exim is built with support for internationalised mail names,
+the availability therof is advertised in
+response to EHLO only to those client hosts that match this option. See
+chapter &<<CHAPi18n>>& for details of Exim's support for internationalisation.
+.wen
+
+
.option spamd_address main string "see below"
This option is available when Exim is compiled with the content-scanning
extension. It specifies how Exim connects to SpamAssassin's &%spamd%& daemon.
unfortunately not all, operating systems.
-.option tls_advertise_hosts main "host list&!!" unset
+.new
+.option tls_advertise_hosts main "host list&!!" *
+.wen
.cindex "TLS" "advertising"
.cindex "encryption" "on SMTP connection"
.cindex "SMTP" "encrypted connection"
of the STARTTLS command to set up an encrypted session is advertised in
response to EHLO only to those client hosts that match this option. See
chapter &<<CHAPTLS>>& for details of Exim's support for TLS.
+.new
+Note that the default value requires that a certificate be supplied
+using the &%tls_certificate%& option. If no certificate is available then
+the &%tls_advertise_hosts%& option should be set empty.
+.wen
.option tls_certificate main string&!! unset
acceptable bound from 1024 to 2048.
+.option tls_eccurve main string&!! prime256v1
+.cindex TLS "EC cryptography"
+If built with a recent-enough version of OpenSSL,
+this option selects a EC curve for use by Exim.
+
+Curve names of the form &'prime256v1'& are accepted.
+For even more-recent library versions, names of the form &'P-512'&
+are also accepted, plus the special value &'auto'&
+which tell the library to choose.
+
+If the option is set to an empty string, no EC curves will be enabled.
+
+
+.option tls_ocsp_file main string&!! unset
+.cindex TLS "certificate status"
+.cindex TLS "OCSP proof file"
+This option
+must if set expand to the absolute path to a file which contains a current
+status proof for the server's certificate, as obtained from the
+Certificate Authority.
+
+.new
+Usable for GnuTLS 3.4.4 or 3.3.17 or OpenSSL 1.1.0 (or later).
+.wen
+
+
.option tls_on_connect_ports main "string list" unset
+.cindex SSMTP
+.cindex SMTPS
This option specifies a list of incoming SSMTP (aka SMTPS) ports that should
operate the obsolete SSMTP (SMTPS) protocol, where a TLS session is immediately
set up without waiting for the client to issue a STARTTLS command. For
See &%tls_verify_hosts%& below.
-.option tls_verify_certificates main string&!! unset
+.option tls_verify_certificates main string&!! system
.cindex "TLS" "client certificate verification"
.cindex "certificate" "verification of client"
-The value of this option is expanded, and must then be the absolute path to
-a file containing permitted certificates for clients that
-match &%tls_verify_hosts%& or &%tls_try_verify_hosts%&. Alternatively, if you
-are using OpenSSL, you can set &%tls_verify_certificates%& to the name of a
-directory containing certificate files. This does not work with GnuTLS; the
-option must be set to the name of a single file if you are using GnuTLS.
+The value of this option is expanded, and must then be either the
+word "system"
+or the absolute path to
+a file or directory containing permitted certificates for clients that
+match &%tls_verify_hosts%& or &%tls_try_verify_hosts%&.
+
+The "system" value for the option will use a
+system default location compiled into the SSL library.
+This is not available for GnuTLS versions preceding 3.0.20,
+and will be taken as empty; an explicit location
+must be specified.
+
+The use of a directory for the option value is not available for GnuTLS versions
+preceding 3.3.6 and a single file must be used.
+
+With OpenSSL the certificates specified
+explicitly
+either by file or directory
+are added to those given by the system default location.
These certificates should be for the certificate authorities trusted, rather
than the public cert of individual clients. With both OpenSSL and GnuTLS, if
the value is a file then the certificates are sent by Exim as a server to
connecting clients, defining the list of accepted certificate authorities.
Thus the values defined should be considered public data. To avoid this,
-use OpenSSL with a directory.
+use the explicit directory version.
See &<<SECTtlssni>>& for discussion of when this option might be re-expanded.
of the other precondition options are common special cases that could in fact
be specified using &%condition%&.
+Historical note: We have &%condition%& on ACLs and on Routers. Routers
+are far older, and use one set of semantics. ACLs are newer and when
+they were created, the ACL &%condition%& process was given far stricter
+parse semantics. The &%bool{}%& expansion condition uses the same rules as
+ACLs. The &%bool_lax{}%& expansion condition uses the same rules as
+Routers. More pointedly, the &%bool_lax{}%& was written to match the existing
+Router rules processing behavior.
+
+This is best illustrated in an example:
+.code
+# If used in an ACL condition will fail with a syntax error, but
+# in a router condition any extra characters are treated as a string
+
+$ exim -be '${if eq {${lc:GOOGLE.com}} {google.com}} {yes} {no}}'
+true {yes} {no}}
+
+$ exim -be '${if eq {${lc:WHOIS.com}} {google.com}} {yes} {no}}'
+ {yes} {no}}
+.endd
+In each example above, the &%if%& statement actually ends after
+&"{google.com}}"&. Since no true or false braces were defined, the
+default &%if%& behavior is to return a boolean true or a null answer
+(which evaluates to false). The rest of the line is then treated as a
+string. So the first example resulted in the boolean answer &"true"&
+with the string &" {yes} {no}}"& appended to it. The second example
+resulted in the null output (indicating false) with the string
+&" {yes} {no}}"& appended to it.
+
+In fact you can put excess forward braces in too. In the router
+&%condition%&, Exim's parser only looks for &"{"& symbols when they
+mean something, like after a &"$"& or when required as part of a
+conditional. But otherwise &"{"& and &"}"& are treated as ordinary
+string characters.
+
+Thus, in a Router, the above expansion strings will both always evaluate
+true, as the result of expansion is a non-empty string which doesn't
+match an explicit false value. This can be tricky to debug. By
+contrast, in an ACL either of those strings will always result in an
+expansion error because the result doesn't look sufficiently boolean.
+
.option debug_print routers string&!! unset
.cindex "testing" "variables in drivers"
unless you really, really know what you are doing. See also the generic
transport option of the same name.
+.option dnssec_request_domains routers "domain list&!!" unset
+.cindex "MX record" "security"
+.cindex "DNSSEC" "MX lookup"
+.cindex "security" "MX lookup"
+.cindex "DNS" "DNSSEC"
+DNS lookups for domains matching &%dnssec_request_domains%& will be done with
+the dnssec request bit set.
+This applies to all of the SRV, MX, AAAA, A lookup sequence.
+
+.option dnssec_require_domains routers "domain list&!!" unset
+.cindex "MX record" "security"
+.cindex "DNSSEC" "MX lookup"
+.cindex "security" "MX lookup"
+.cindex "DNS" "DNSSEC"
+DNS lookups for domains matching &%dnssec_request_domains%& will be done with
+the dnssec request bit set. Any returns not having the Authenticated Data bit
+(AD bit) set will be ignored and logged as a host-lookup failure.
+This applies to all of the SRV, MX, AAAA, A lookup sequence.
+
.option domains routers&!? "domain list&!!" unset
.cindex "router" "restricting to specific domains"
to be used.
+.option dsn_lasthop routers boolean false
+.cindex "DSN" "success"
+.cindex "Delivery Status Notification" "success"
+If this option is set true, and extended DSN (RFC3461) processing is in effect,
+Exim will not pass on DSN requests to downstream DSN-aware hosts but will
+instead send a success DSN as if the next hop does not support DSN.
+Not effective on redirect routers.
+
+
.option errors_to routers string&!! unset
.cindex "envelope sender"
.option headers_add routers list&!! unset
.cindex "header lines" "adding"
.cindex "router" "adding header lines"
-This option specifies a list of text headers, newline-separated,
+This option specifies a list of text headers,
+newline-separated (by default, changeable in the usual way),
that is associated with any addresses that are accepted by the router.
Each item is separately expanded, at routing time. However, this
option has no effect when an address is just being verified. The way in which
.option headers_remove routers list&!! unset
.cindex "header lines" "removing"
.cindex "router" "removing header lines"
-This option specifies a list of text headers, colon-separated,
+This option specifies a list of text headers,
+colon-separated (by default, changeable in the usual way),
that is associated with any addresses that are accepted by the router.
Each item is separately expanded, at routing time. However, this
option has no effect when an address is just being verified. The way in which
routers, and this can lead to problems with duplicates -- see the similar
warning for &%headers_add%& above.
+&*Warning 3*&: Because of the separate expansion of the list items,
+items that contain a list separator must have it doubled.
+To avoid this, change the list separator (&<<SECTlistsepchange>>&).
+
+
.option ignore_target_hosts routers "host list&!!" unset
.cindex "IP address" "discarding"
or testing recipient verification using &%-bv%&.
See section &<<SECTrouprecon>>& for a list of the order in which preconditions
are evaluated.
+See also the &$verify_mode$& variable.
.option verify_sender routers&!? boolean true
or testing sender verification using &%-bvs%&.
See section &<<SECTrouprecon>>& for a list of the order in which preconditions
are evaluated.
+See also the &$verify_mode$& variable.
.ecindex IIDgenoprou1
.ecindex IIDgenoprou2
.section "Problems with DNS lookups" "SECTprowitdnsloo"
There have been problems with DNS servers when SRV records are looked up.
-Some mis-behaving servers return a DNS error or timeout when a non-existent
+Some misbehaving servers return a DNS error or timeout when a non-existent
SRV record is sought. Similar problems have in the past been reported for
MX records. The global &%dns_again_means_nonexist%& option can help with this
problem, but it is heavy-handed because it is a global option.
an address; if such a router is expected to handle "all remaining non-local
domains", then it is important to set &%no_more%&.
+The router will defer rather than decline if the domain
+is found in the &%fail_defer_domains%& router option.
+
Reasons for a &(dnslookup)& router to decline currently include:
.ilist
The domain does not exist in DNS
-.option dnssec_request_domains dnslookup "domain list&!!" unset
-.cindex "MX record" "security"
-.cindex "DNSSEC" "MX lookup"
-.cindex "security" "MX lookup"
-.cindex "DNS" "DNSSEC"
-DNS lookups for domains matching &%dnssec_request_domains%& will be done with
-the dnssec request bit set.
-This applies to all of the SRV, MX A6, AAAA, A lookup sequence.
-
-
-
-.option dnssec_require_domains dnslookup "domain list&!!" unset
-.cindex "MX record" "security"
-.cindex "DNSSEC" "MX lookup"
-.cindex "security" "MX lookup"
-.cindex "DNS" "DNSSEC"
-DNS lookups for domains matching &%dnssec_request_domains%& will be done with
-the dnssec request bit set. Any returns not having the Authenticated Data bit
-(AD bit) set wil be ignored and logged as a host-lookup failure.
-This applies to all of the SRV, MX A6, AAAA, A lookup sequence.
+.option fail_defer_domains dnslookup "domain list&!!" unset
+.cindex "MX record" "not found"
+DNS lookups for domains matching &%fail_defer_domains%&
+which find no matching record will cause the router to defer
+rather than the default behaviour of decline.
+This maybe be useful for queueing messages for a newly created
+domain while the DNS configuration is not ready.
+However, it will result in any message with mistyped domains
+also being queued.
.option mx_domains dnslookup "domain list&!!" unset
files and pipes, and for generating autoreplies. See the &%file_transport%&,
&%pipe_transport%& and &%reply_transport%& descriptions below.
+If success DSNs have been requested
+.cindex "DSN" "success"
+.cindex "Delivery Status Notification" "success"
+redirection triggers one and the DSN options are not passed any further.
+
.section "Redirection data" "SECID124"
.cindex "black hole"
.cindex "abandoning mail"
&':blackhole:'& can be used. It does what its name implies. No delivery is
-done, and no error message is generated. This has the same effect as specifing
+done, and no error message is generated. This has the same effect as specifying
&_/dev/null_& as a destination, but it can be independently disabled.
&*Warning*&: If &':blackhole:'& appears anywhere in a redirection list, no
.option headers_add transports list&!! unset
.cindex "header lines" "adding in transport"
.cindex "transport" "header lines; adding"
-This option specifies a list of text headers, newline-separated,
+This option specifies a list of text headers,
+newline-separated (by default, changeable in the usual way),
which are (separately) expanded and added to the header
portion of a message as it is transported, as described in section
&<<SECTheadersaddrem>>&. Additional header lines can also be specified by
.option headers_remove transports list&!! unset
.cindex "header lines" "removing"
.cindex "transport" "header lines; removing"
-This option specifies a list of header names, colon-separated;
+This option specifies a list of header names,
+colon-separated (by default, changeable in the usual way);
these headers are omitted from the message as it is transported, as described
in section &<<SECTheadersaddrem>>&. Header removal can also be specified by
routers.
Unlike most options, &%headers_remove%& can be specified multiple times
for a router; all listed headers are removed.
+&*Warning*&: Because of the separate expansion of the list items,
+items that contain a list separator must have it doubled.
+To avoid this, change the list separator (&<<SECTlistsepchange>>&).
+
.option headers_rewrite transports string unset
to ensure that any additional groups associated with the uid are set up.
+.new
+.option max_parallel transports integer&!! unset
+.cindex limit "transport parallelism"
+.cindex transport "parallel processes"
+.cindex transport "concurrency limit"
+.cindex "delivery" "parallelism for transport"
+If this option is set and expands to an integer greater than zero
+it limits the number of concurrent runs of the transport.
+The control does not apply to shadow transports.
+
+.cindex "hints database" "transport concurrency control"
+Exim implements this control by means of a hints database in which a record is
+incremented whenever a transport process is beaing created. The record
+is decremented and possibly removed when the process terminates.
+Obviously there is scope for
+records to get left lying around if there is a system or program crash. To
+guard against this, Exim ignores any records that are more than six hours old.
+
+If you use this option, you should also arrange to delete the
+relevant hints database whenever your system reboots. The names of the files
+start with &_misc_& and they are kept in the &_spool/db_& directory. There
+may be one or two files, depending on the type of DBM in use. The same files
+are used for ETRN and smtp transport serialization.
+.wen
+
+
.option message_size_limit transports string&!! 0
.cindex "limit" "message size per transport"
.cindex "size" "of message, limit"
This option sets up a filtering (in the Unix shell sense) process for messages
at transport time. It should not be confused with mail filtering as set up by
individual users or via a system filter.
+.new
+If unset, or expanding to an empty string, no filtering is done.
+.wen
When the message is about to be written out, the command specified by
&%transport_filter%& is started up in a separate, parallel process, and
delivery, the two pipe transports may be run concurrently. You must ensure that
any pipe commands you set up are robust against this happening. If the commands
write to a file, the &%exim_lock%& utility might be of use.
+.new
+Alternatively the &%max_parallel%& option could be used with a value
+of "1" to enforce serialization.
+.wen
&%force_command%& is set, expanding out to the original argument vector as
separate items, similarly to a Unix shell &`"$@"`& construct.
+
.option ignore_status pipe boolean false
If this option is true, the status returned by the subprocess that is set up to
run the command is ignored, and Exim behaves as if zero had been returned.
&*Note*&: This option does not apply to timeouts, which do not return a status.
See the &%timeout_defer%& option for how timeouts are handled.
+
.option log_defer_output pipe boolean false
.cindex "&(pipe)& transport" "logging output"
If this option is set, and the status returned by the command is
one of the codes listed in &%temp_errors%& (that is, delivery was deferred),
-and any output was produced, the first line of it is written to the main log.
+and any output was produced on stdout or stderr, the first line of it is
+written to the main log.
.option log_fail_output pipe boolean false
-If this option is set, and the command returns any output, and also ends with a
-return code that is neither zero nor one of the return codes listed in
-&%temp_errors%& (that is, the delivery failed), the first line of output is
-written to the main log. This option and &%log_output%& are mutually exclusive.
-Only one of them may be set.
-
+If this option is set, and the command returns any output on stdout or
+stderr, and also ends with a return code that is neither zero nor one of
+the return codes listed in &%temp_errors%& (that is, the delivery
+failed), the first line of output is written to the main log. This
+option and &%log_output%& are mutually exclusive. Only one of them may
+be set.
.option log_output pipe boolean false
-If this option is set and the command returns any output, the first line of
-output is written to the main log, whatever the return code. This option and
-&%log_fail_output%& are mutually exclusive. Only one of them may be set.
-
+If this option is set and the command returns any output on stdout or
+stderr, the first line of output is written to the main log, whatever
+the return code. This option and &%log_fail_output%& are mutually
+exclusive. Only one of them may be set.
.option max_output pipe integer 20K
details.
+.option dnssec_request_domains smtp "domain list&!!" unset
+.cindex "MX record" "security"
+.cindex "DNSSEC" "MX lookup"
+.cindex "security" "MX lookup"
+.cindex "DNS" "DNSSEC"
+DNS lookups for domains matching &%dnssec_request_domains%& will be done with
+the dnssec request bit set.
+This applies to all of the SRV, MX, AAAA, A lookup sequence.
+
+
+
+.option dnssec_require_domains smtp "domain list&!!" unset
+.cindex "MX record" "security"
+.cindex "DNSSEC" "MX lookup"
+.cindex "security" "MX lookup"
+.cindex "DNS" "DNSSEC"
+DNS lookups for domains matching &%dnssec_request_domains%& will be done with
+the dnssec request bit set. Any returns not having the Authenticated Data bit
+(AD bit) set will be ignored and logged as a host-lookup failure.
+This applies to all of the SRV, MX, AAAA, A lookup sequence.
+
+
+
.option dscp smtp string&!! unset
.cindex "DCSP" "outbound"
This option causes the DSCP value associated with a socket to be set to one
Exim will not try to start a TLS session when delivering to any host that
matches this list. See chapter &<<CHAPTLS>>& for details of TLS.
-.option hosts_verify_avoid_tls smtp "host list&!!" *
+.option hosts_verify_avoid_tls smtp "host list&!!" unset
.cindex "TLS" "avoiding for certain hosts"
Exim will not try to start a TLS session for a verify callout,
or when delivering in cutthrough mode,
to any host that matches this list.
-Note that the default is to not use TLS.
.option hosts_max_try smtp integer 5
&<<CHAPSMTPAUTH>>& for details of authentication.
+.option hosts_request_ocsp smtp "host list&!!" *
+.cindex "TLS" "requiring for certain servers"
+Exim will request a Certificate Status on a
+TLS session for any host that matches this list.
+&%tls_verify_certificates%& should also be set for the transport.
+
+.option hosts_require_ocsp smtp "host list&!!" unset
+.cindex "TLS" "requiring for certain servers"
+Exim will request, and check for a valid Certificate Status being given, on a
+TLS session for any host that matches this list.
+&%tls_verify_certificates%& should also be set for the transport.
+
.option hosts_require_tls smtp "host list&!!" unset
.cindex "TLS" "requiring for certain servers"
Exim will insist on using a TLS session when delivering to any host that
unauthenticated. See also &%hosts_require_auth%&, and chapter
&<<CHAPSMTPAUTH>>& for details of authentication.
+.option hosts_try_prdr smtp "host list&!!" *
+.cindex "PRDR" "enabling, optional in client"
+This option provides a list of servers to which, provided they announce
+PRDR support, Exim will attempt to negotiate PRDR
+for multi-recipient messages.
+The option can usually be left as default.
+
.option interface smtp "string list&!!" unset
.cindex "bind IP address"
.cindex "IP address" "binding"
permits this.
-.option multi_domain smtp boolean true
+.option multi_domain smtp boolean&!! true
.vindex "&$domain$&"
When this option is set, the &(smtp)& transport can handle a number of
addresses containing a mixture of different domains provided they all resolve
&$domain$& in an expansion for the transport, because it is set only when there
is a single domain involved in a remote delivery.
+It is expanded per-address and can depend on any of
+&$address_data$&, &$domain_data$&, &$local_part_data$&,
+&$host$&, &$host_address$& and &$host_port$&.
.option port smtp string&!! "see below"
.cindex "port" "sending TCP/IP"
deliveries into closed message stores. Exim also has support for running LMTP
over a pipe to a local process &-- see chapter &<<CHAPLMTP>>&.
-If this option is set to &"smtps"&, the default vaule for the &%port%& option
+If this option is set to &"smtps"&, the default value for the &%port%& option
changes to &"smtps"&, and the transport initiates TLS immediately after
connecting, as an outbound SSL-on-connect, instead of using STARTTLS to upgrade.
The Internet standards bodies strongly discourage use of this mode.
-.option retry_include_ip_address smtp boolean true
+.option retry_include_ip_address smtp boolean&!! true
Exim normally includes both the host name and the IP address in the key it
constructs for indexing retry data after a temporary delivery failure. This
means that when one of several IP addresses for a host is failing, it gets
However, in some dialup environments hosts are assigned a different IP address
each time they connect. In this situation the use of the IP address as part of
the retry key leads to undesirable behaviour. Setting this option false causes
-Exim to use only the host name. This should normally be done on a separate
-instance of the &(smtp)& transport, set up specially to handle the dialup
-hosts.
+Exim to use only the host name.
+Since it is expanded it can be made to depend on the host or domain.
.option serialize_hosts smtp "host list&!!" unset
may be one or two files, depending on the type of DBM in use. The same files
are used for ETRN serialization.
+.new
+See also the &%max_parallel%& generic transport option.
+.wen
+
.option size_addition smtp integer 1024
.cindex "SMTP" "SIZE"
the use of the SIZE option altogether.
+.new
+.option socks_proxy smtp string&!! unset
+.cindex proxy SOCKS
+This option enables use of SOCKS proxies for connections made by the
+transport. For details see &<<SECTproxySOCKS>>&.
+.wen
+
+
.option tls_certificate smtp string&!! unset
.cindex "TLS" "client certificate, location of"
.cindex "certificate" "client, location of"
in clear.
-.option tls_try_verify_hosts smtp "host list&!! unset
+.option tls_try_verify_hosts smtp "host list&!!" *
.cindex "TLS" "server certificate verification"
.cindex "certificate" "verification of server"
This option gives a list of hosts for which, on encrypted connections,
certificate verification will be tried but need not succeed.
The &%tls_verify_certificates%& option must also be set.
+Note that unless the host is in this list
+TLS connections will be denied to hosts using self-signed certificates
+when &%tls_verify_certificates%& is matched.
+The &$tls_out_certificate_verified$& variable is set when
+certificate verification succeeds.
+
+
+.option tls_verify_cert_hostnames smtp "host list&!!" *
+.cindex "TLS" "server certificate hostname verification"
+.cindex "certificate" "verification of server"
+This option give a list of hosts for which,
+while verifying the server certificate,
+checks will be included on the host name
+(note that this will generally be the result of a DNS MX lookup)
+versus Subject and Subject-Alternate-Name fields. Wildcard names are permitted
+limited to being the initial component of a 3-or-more component FQDN.
+There is no equivalent checking on client certificates.
-.option tls_verify_certificates smtp string&!! unset
+
+.option tls_verify_certificates smtp string&!! system
.cindex "TLS" "server certificate verification"
.cindex "certificate" "verification of server"
.vindex "&$host$&"
.vindex "&$host_address$&"
-The value of this option must be the absolute path to a file containing
-permitted server certificates, for use when setting up an encrypted connection.
-Alternatively, if you are using OpenSSL, you can set
-&%tls_verify_certificates%& to the name of a directory containing certificate
-files. This does not work with GnuTLS; the option must be set to the name of a
-single file if you are using GnuTLS. The values of &$host$& and
+The value of this option must be either the
+word "system"
+or the absolute path to
+a file or directory containing permitted certificates for servers,
+for use when setting up an encrypted connection.
+
+The "system" value for the option will use a location compiled into the SSL library.
+This is not available for GnuTLS versions preceding 3.0.20; a value of "system"
+is taken as empty and an explicit location
+must be specified.
+
+The use of a directory for the option value is not available for GnuTLS versions
+preceding 3.3.6 and a single file must be used.
+
+With OpenSSL the certificates specified
+explicitly
+either by file or directory
+are added to those given by the system default location.
+
+The values of &$host$& and
&$host_address$& are set to the name and address of the server during the
expansion of this option. See chapter &<<CHAPTLS>>& for details of TLS.
-For back-compatability,
+For back-compatibility,
if neither tls_verify_hosts nor tls_try_verify_hosts are set
+(a single-colon empty list counts as being set)
and certificate verification fails the TLS connection is closed.
-.option tls_verify_hosts smtp "host list&!! unset
+.option tls_verify_hosts smtp "host list&!!" unset
.cindex "TLS" "server certificate verification"
.cindex "certificate" "verification of server"
This option gives a list of hosts for which. on encrypted connections,
2822 address, including the angle brackets if necessary. If text outside angle
brackets contains a character whose value is greater than 126 or less than 32
(except for tab), the text is encoded according to RFC 2047. The character set
-is taken from &%headers_charset%&, which defaults to ISO-8859-1.
+is taken from &%headers_charset%&, which gets its default at build time.
When the &"w"& flag is set on a rule that causes an envelope address to be
rewritten, all but the working part of the replacement address is discarded.
legitimate reasons for this (host died, network died), but if it repeats a lot
for the same host, it indicates something odd.
+.vitem &%lookup%&
+A DNS lookup for a host failed.
+Note that a &%dnslookup%& router will need to have matched
+its &%fail_defer_domains%& option for this retry type to be usable.
+Also note that a &%manualroute%& router will probably need
+its &%host_find_failed%& option set to &%defer%&.
+
.vitem &%refused_MX%&
A connection to a host obtained from an MX record was refused.
AUTH_HEIMDAL_GSSAPI=yes
AUTH_PLAINTEXT=yes
AUTH_SPA=yes
+AUTH_TLS=yes
.endd
in &_Local/Makefile_&, respectively. The first of these supports the CRAM-MD5
authentication mechanism (RFC 2195), and the second provides an interface to
the PLAIN authentication mechanism (RFC 2595) or the LOGIN mechanism, which is
not formally documented, but used by several MUAs. The seventh authenticator
supports Microsoft's &'Secure Password Authentication'& mechanism.
+The eighth is an Exim authenticator but not an SMTP one;
+instead it can use information from a TLS negotiation.
The authenticators are configured using the same syntax as other drivers (see
section &<<SECTfordricon>>&). If no authenticators are required, no
.option client_set_id authenticators string&!! unset
When client authentication succeeds, this condition is expanded; the
-result is used in the log lines for outbound messasges.
+result is used in the log lines for outbound messages.
Typically it will be the user name used for authentication.
driver = cram_md5
public_name = CRAM-MD5
server_secret = ${lookup{$auth1:mail.example.org:userPassword}\
- dbmjz{/etc/sasldb2}}
+ dbmjz{/etc/sasldb2}{$value}fail}
server_set_id = $auth1
.endd
.scindex IIDdcotauth2 "authenticators" "&(dovecot)&"
This authenticator is an interface to the authentication facility of the
Dovecot POP/IMAP server, which can support a number of authentication methods.
+Note that Dovecot must be configured to use auth-client not auth-userdb.
If you are using Dovecot to authenticate POP/IMAP clients, it might be helpful
to use the same mechanisms for SMTP authentication. This is a server
authenticator only. There is only one option:
driver = dovecot
public_name = PLAIN
server_socket = /var/run/dovecot/auth-client
- server_set_id = $auth2
+ server_set_id = $auth1
dovecot_ntlm:
driver = dovecot
.option server_service heimdal_gssapi string&!! "smtp"
This option specifies the service identifier used, in conjunction with
-&%server_hostname%&, for building the identifer for finding credentials
+&%server_hostname%&, for building the identifier for finding credentials
from the keytab.
+. ////////////////////////////////////////////////////////////////////////////
+. ////////////////////////////////////////////////////////////////////////////
+
+.chapter "The tls authenticator" "CHAPtlsauth"
+.scindex IIDtlsauth1 "&(tls)& authenticator"
+.scindex IIDtlsauth2 "authenticators" "&(tls)&"
+.cindex "authentication" "Client Certificate"
+.cindex "authentication" "X509"
+.cindex "Certificate-based authentication"
+The &(tls)& authenticator provides server support for
+authentication based on client certificates.
+
+It is not an SMTP authentication mechanism and is not
+advertised by the server as part of the SMTP EHLO response.
+It is an Exim authenticator in the sense that it affects
+the protocol element of the log line, can be tested for
+by the &%authenticated%& ACL condition, and can set
+the &$authenticated_id$& variable.
+
+The client must present a verifiable certificate,
+for which it must have been requested via the
+&%tls_verify_hosts%& or &%tls_try_verify_hosts%& main options
+(see &<<CHAPTLS>>&).
+
+If an authenticator of this type is configured it is
+run before any SMTP-level communication is done,
+and can authenticate the connection.
+If it does, SMTP authentication is not offered.
+
+A maximum of one authenticator of this type may be present.
+
+
+.cindex "options" "&(tls)& authenticator (server)"
+The &(tls)& authenticator has three server options:
+
+.option server_param1 tls string&!! unset
+.cindex "variables (&$auth1$& &$auth2$& etc)" "in &(tls)& authenticator"
+This option is expanded after the TLS negotiation and
+the result is placed in &$auth1$&.
+If the expansion is forced to fail, authentication fails. Any other expansion
+failure causes a temporary error code to be returned.
+
+.option server_param2 tls string&!! unset
+.option server_param3 tls string&!! unset
+As above, for &$auth2$& and &$auth3$&.
+
+&%server_param1%& may also be spelled &%server_param%&.
+
+
+Example:
+.code
+tls:
+ driver = tls
+ server_param1 = ${certextract {subj_altname,mail,>:} \
+ {$tls_in_peercert}}
+ server_condition = ${if forany {$auth1} \
+ {!= {0} \
+ {${lookup ldap{ldap:///\
+ mailname=${quote_ldap_dn:${lc:$item}},\
+ ou=users,LDAP_DC?mailid} {$value}{0} \
+ } } } }
+ server_set_id = ${if = {1}{${listcount:$auth1}} {$auth1}{}}
+.endd
+.ecindex IIDtlsauth1
+.ecindex IIDtlsauth2
+
+
+Note that because authentication is traditionally an SMTP operation,
+the &%authenticated%& ACL condition cannot be used in
+a connect- or helo-ACL.
+
+
+
. ////////////////////////////////////////////////////////////////////////////
. ////////////////////////////////////////////////////////////////////////////
There are some differences in usage when using GnuTLS instead of OpenSSL:
.ilist
-The &%tls_verify_certificates%& option must contain the name of a file, not the
-name of a directory (for OpenSSL it can be either).
+The &%tls_verify_certificates%& option
+cannot be the path of a directory
+for GnuTLS versions before 3.3.6
+(for later versions, or OpenSSL, it can be either).
.next
The default value for &%tls_dhparam%& differs for historical reasons.
.next
as part of the &[gnutls_priority_init]& function. This is very similar to the
ciphersuite specification in OpenSSL.
-The &%tls_require_ciphers%& option is treated as the GnuTLS priority string.
+The &%tls_require_ciphers%& option is treated as the GnuTLS priority string
+and controls both protocols and ciphers.
The &%tls_require_ciphers%& option is available both as an global option,
controlling how Exim behaves as a server, and also as an option of the
&url(http://www.gnutls.org/manual/gnutls.html#Listing-the-ciphersuites-in-a-priority-string, then the example code)
on that site can be used to test a given string.
+For example:
+.code
+# Disable older versions of protocols
+tls_require_ciphers = NORMAL:%LATEST_RECORD_VERSION:-VERS-SSL3.0
+.endd
+
Prior to Exim 4.80, an older API of GnuTLS was used, and Exim supported three
additional options, "&%gnutls_require_kx%&", "&%gnutls_require_mac%&" and
"&%gnutls_require_protocols%&". &%tls_require_ciphers%& was an Exim list.
These options are, in fact, expanded strings, so you can make them depend on
the identity of the client that is connected if you wish. The first file
contains the server's X509 certificate, and the second contains the private key
-that goes with it. These files need to be readable by the Exim user, and must
-always be given as full path names. They can be the same file if both the
+that goes with it. These files need to be
+PEM format and readable by the Exim user, and must
+always be given as full path names.
+The key must not be password-protected.
+They can be the same file if both the
certificate and the key are contained within it. If &%tls_privatekey%& is not
set, or if its expansion is forced to fail or results in an empty string, this
is assumed to be the case. The certificate file may also contain intermediate
apply to all TLS connections. For any host that matches one of these options,
Exim requests a certificate as part of the setup of the TLS session. The
contents of the certificate are verified by comparing it with a list of
-expected certificates. These must be available in a file or,
-for OpenSSL only (not GnuTLS), a directory, identified by
+expected certificates.
+These may be the system default set (depending on library version),
+an explicit file or,
+depending on library version, a directory, identified by
&%tls_verify_certificates%&.
A file can contain multiple certificates, concatenated end to end. If a
.cindex "TLS" "revoked certificates"
.cindex "revocation list"
.cindex "certificate" "revocation list"
+.cindex "OCSP" "stapling"
Certificate issuing authorities issue Certificate Revocation Lists (CRLs) when
certificates are revoked. If you have such a list, you can pass it to an Exim
server using the global option called &%tls_crl%& and to an Exim client using
an identically named option for the &(smtp)& transport. In each case, the value
of the option is expanded and must then be the name of a file that contains a
CRL in PEM format.
+The downside is that clients have to periodically re-download a potentially huge
+file from every certificate authority they know of.
+
+The way with most moving parts at query time is Online Certificate
+Status Protocol (OCSP), where the client verifies the certificate
+against an OCSP server run by the CA. This lets the CA track all
+usage of the certs. It requires running software with access to the
+private key of the CA, to sign the responses to the OCSP queries. OCSP
+is based on HTTP and can be proxied accordingly.
+
+The only widespread OCSP server implementation (known to this writer)
+comes as part of OpenSSL and aborts on an invalid request, such as
+connecting to the port and then disconnecting. This requires
+re-entering the passphrase each time some random client does this.
+
+The third way is OCSP Stapling; in this, the server using a certificate
+issued by the CA periodically requests an OCSP proof of validity from
+the OCSP server, then serves it up inline as part of the TLS
+negotiation. This approach adds no extra round trips, does not let the
+CA track users, scales well with number of certs issued by the CA and is
+resilient to temporary OCSP server failures, as long as the server
+starts retrying to fetch an OCSP proof some time before its current
+proof expires. The downside is that it requires server support.
+
+Unless Exim is built with the support disabled,
+.new
+or with GnuTLS earlier than version 3.3.16 / 3.4.8
+.wen
+support for OCSP stapling is included.
+
+There is a global option called &%tls_ocsp_file%&.
+The file specified therein is expected to be in DER format, and contain
+an OCSP proof. Exim will serve it as part of the TLS handshake. This
+option will be re-expanded for SNI, if the &%tls_certificate%& option
+contains &`tls_in_sni`&, as per other TLS options.
+
+Exim does not at this time implement any support for fetching a new OCSP
+proof. The burden is on the administrator to handle this, outside of
+Exim. The file specified should be replaced atomically, so that the
+contents are always valid. Exim will expand the &%tls_ocsp_file%& option
+on each connection, so a new file will be handled transparently on the
+next connection.
+
+When built with OpenSSL Exim will check for a valid next update timestamp
+in the OCSP proof; if not present, or if the proof has expired, it will be
+ignored.
+
+For the client to be able to verify the stapled OCSP the server must
+also supply, in its stapled information, any intermediate
+certificates for the chain leading to the OCSP proof from the signer
+of the server certificate. There may be zero or one such. These
+intermediate certificates should be added to the server OCSP stapling
+file named by &%tls_ocsp_file%&.
+
+Note that the proof only covers the terminal server certificate,
+not any of the chain from CA to it.
+
+There is no current way to staple a proof for a client certificate.
+
+.code
+ A helper script "ocsp_fetch.pl" for fetching a proof from a CA
+ OCSP server is supplied. The server URL may be included in the
+ server certificate, if the CA is helpful.
+
+ One failure mode seen was the OCSP Signer cert expiring before the end
+ of validity of the OCSP proof. The checking done by Exim/OpenSSL
+ noted this as invalid overall, but the re-fetch script did not.
+.endd
+
+
.section "Configuring an Exim client to use TLS" "SECID185"
&%tls_verify_hosts%& or &%tls_try_verify_hosts%& matches the client.
If the &%tls_verify_certificates%& option is set on the &(smtp)& transport, it
+specifies a collection of expected server certificates.
+These may be the system default set (depending on library version),
+a file or,
+depending on library version, a directory,
must name a file or,
-for OpenSSL only (not GnuTLS), a directory, that contains a collection of
-expected server certificates. The client verifies the server's certificate
+for OpenSSL only (not GnuTLS), a directory.
+The client verifies the server's certificate
against this collection, taking into account any revoked certificates that are
in the list defined by &%tls_crl%&.
Failure to verify fails the TLS connection unless either of the
certificate verification to the listed servers. Verification either must
or need not succeed respectively.
+The &(smtp)& transport has two OCSP-related options:
+&%hosts_require_ocsp%&; a host-list for which a Certificate Status
+is requested and required for the connection to proceed. The default
+value is empty.
+&%hosts_request_ocsp%&; a host-list for which (additionally)
+a Certificate Status is requested (but not necessarily verified). The default
+value is "*" meaning that requests are made unless configured
+otherwise.
+
+The host(s) should also be in &%hosts_require_tls%&, and
+&%tls_verify_certificates%& configured for the transport,
+for OCSP to be relevant.
+
If
&%tls_require_ciphers%& is set on the &(smtp)& transport, it must contain a
list of permitted cipher suites. If either of these checks fails, delivery to
within and possibly choose to use different certificates and keys (and more)
for this session.
-This is analagous to HTTP's &"Host:"& header, and is the main mechanism by
+This is analogous to HTTP's &"Host:"& header, and is the main mechanism by
which HTTPS-enabled web-sites can be virtual-hosted, many sites to one IP
address.
.next
.vindex "&%tls_verify_certificates%&"
&%tls_verify_certificates%&
+.next
+.vindex "&%tls_ocsp_file%&"
+&%tls_ocsp_file%&
.endlist
Great care should be taken to deal with matters of case, various injection
The Exim developers are proceeding cautiously and so far no other TLS options
are re-expanded.
-When Exim is built againt OpenSSL, OpenSSL must have been built with support
+When Exim is built against OpenSSL, OpenSSL must have been built with support
for TLS Extensions. This holds true for OpenSSL 1.0.0+ and 0.9.8+ with
enable-tlsext in EXTRACONFIGURE. If you invoke &(openssl s_client -h)& and
see &`-servername`& in the output, then OpenSSL has support.
.cindex "EXPN" "ACL for"
.cindex "HELO" "ACL for"
.cindex "EHLO" "ACL for"
+.cindex "DKIM" "ACL for"
.cindex "MAIL" "ACL for"
.cindex "QUIT, ACL for"
.cindex "RCPT" "ACL for"
.cindex "SMTP" "connection, ACL for"
.cindex "non-SMTP messages" "ACLs for"
.cindex "MIME content scanning" "ACL for"
+.cindex "PRDR" "ACL for"
.table2 140pt
.irow &%acl_not_smtp%& "ACL for non-SMTP messages"
.irow &%acl_smtp_auth%& "ACL for AUTH"
.irow &%acl_smtp_connect%& "ACL for start of SMTP connection"
.irow &%acl_smtp_data%& "ACL after DATA is complete"
+.irow &%acl_smtp_data_prdr%& "ACL for each recipient, after DATA is complete"
+.irow &%acl_smtp_dkim%& "ACL for each DKIM signer"
.irow &%acl_smtp_etrn%& "ACL for ETRN"
.irow &%acl_smtp_expn%& "ACL for EXPN"
.irow &%acl_smtp_helo%& "ACL for HELO or EHLO"
and try again later, but that is their problem, though it does waste some of
your resources.
-The &%acl_smtp_data%& ACL is run after both the &%acl_smtp_dkim%& and
-the &%acl_smtp_mime%& ACLs.
+The &%acl_smtp_data%& ACL is run after
+the &%acl_smtp_data_prdr%&,
+the &%acl_smtp_dkim%&
+and the &%acl_smtp_mime%& ACLs.
.section "The SMTP DKIM ACL" "SECTDKIMACL"
The &%acl_smtp_dkim%& ACL is available only when Exim is compiled with DKIM support
This ACL is evaluated after &%acl_smtp_dkim%& but before &%acl_smtp_data%&.
+.section "The SMTP PRDR ACL" "SECTPRDRACL"
+.cindex "PRDR" "ACL for"
+.oindex "&%prdr_enable%&"
+The &%acl_smtp_data_prdr%& ACL is available only when Exim is compiled
+with PRDR support enabled (which is the default).
+It becomes active only when the PRDR feature is negotiated between
+client and server for a message, and more than one recipient
+has been accepted.
+
+The ACL test specified by &%acl_smtp_data_prdr%& happens after a message
+has been received, and is executed once for each recipient of the message
+with &$local_part$& and &$domain$& valid.
+The test may accept, defer or deny for individual recipients.
+The &%acl_smtp_data%& will still be called after this ACL and
+can reject the message overall, even if this ACL has accepted it
+for some or all recipients.
+
+PRDR may be used to support per-user content filtering. Without it
+one must defer any recipient after the first that has a different
+content-filter configuration. With PRDR, the RCPT-time check
+.new
+.cindex "PRDR" "variable for"
+for this can be disabled when the variable &$prdr_requested$&
+is &"yes"&.
+.wen
+Any required difference in behaviour of the main DATA-time
+ACL should however depend on the PRDR-time ACL having run, as Exim
+will avoid doing so in some situations (e.g. single-recipient mails).
+
+See also the &%prdr_enable%& global option
+and the &%hosts_try_prdr%& smtp transport option.
+
+This ACL is evaluated after &%acl_smtp_dkim%& but before &%acl_smtp_data%&.
+If the ACL is not defined, processing completes as if
+the feature was not requested by the client.
+
.section "The QUIT ACL" "SECTQUITACL"
.cindex "QUIT, ACL for"
The ACL for the SMTP QUIT command is anomalous, in that the outcome of the ACL
does not affect the response code to QUIT, which is always 221. Thus, the ACL
-does not in fact control any access. For this reason, the only verbs that are
-permitted are &%accept%& and &%warn%&.
+does not in fact control any access.
+For this reason, it may only accept
+or warn as its final result.
This ACL can be used for tasks such as custom logging at the end of an SMTP
session. For example, you can use ACL variables in other ACLs to count
response.
.vindex "&$acl_verify_message$&"
+For ACLs that are called by an &%acl =%& ACL condition, the message is
+stored in &$acl_verify_message$&, from which the calling ACL may use it.
+
If &%message%& is used on a statement that verifies an address, the message
specified overrides any message that is generated by the verification process.
However, the original message is available in the variable
.cindex "&ACL;" "cutthrough routing"
.cindex "cutthrough" "requesting"
This option requests delivery be attempted while the item is being received.
-It is usable in the RCPT ACL and valid only for single-recipient mails forwarded
-from one SMTP connection to another. If a recipient-verify callout connection is
-requested in the same ACL it is held open and used for the data, otherwise one is made
-after the ACL completes.
+
+The option is usable in the RCPT ACL.
+If enabled for a message received via smtp and routed to an smtp transport,
+and only one transport, interface, destination host and port combination
+is used for all recipients of the message,
+then the delivery connection is made while the receiving connection is open
+and data is copied from one to the other.
+
+An attempt to set this option for any recipient but the first
+for a mail will be quietly ignored.
+If a recipient-verify callout connection is subsequently
+requested in the same ACL it is held open and used for
+any subsequent recipients and the data,
+otherwise one is made after the initial RCPT ACL completes.
Note that routers are used in verify mode,
and cannot depend on content of received headers.
Cutthrough delivery is not supported via transport-filters or when DKIM signing
of outgoing messages is done, because it sends data to the ultimate destination
before the entire message has been received from the source.
+It is not supported for messages received with the SMTP PRDR option in use.
Should the ultimate destination system positively accept or reject the mail,
a corresponding indication is given to the source system and nothing is queued.
If there is a temporary error the item is queued for later delivery in the
-usual fashion. If the item is successfully delivered in cutthrough mode the log line
-is tagged with ">>" rather than "=>" and appears before the acceptance "<="
-line.
+usual fashion. If the item is successfully delivered in cutthrough mode
+the delivery log lines are tagged with ">>" rather than "=>" and appear
+before the acceptance "<=" line.
-Delivery in this mode avoids the generation of a bounce mail to a (possibly faked)
+Delivery in this mode avoids the generation of a bounce mail to a
+(possibly faked)
sender when the destination system is doing content-scan based rejection.
&*Note:*& This control applies only to the current message, not to any others
that are being submitted at the same time using &%-bs%& or &%-bS%&.
+
+.new
+.vitem &*control&~=&~utf8_downconvert*&
+This control enables conversion of UTF-8 in message addresses
+to a-label form.
+For details see &<<SECTi18nMTA>>&.
+.wen
.endlist vlist
and $acl_narg is set to the count of values.
Previous values of these variables are restored after the call returns.
The name and values are expanded separately.
+Note that spaces in complex expansions which are used as arguments
+will act as argument separators.
If the nested &%acl%& returns &"drop"& and the outer condition denies access,
the connection is dropped. If it returns &"discard"&, the verb must be
send email. Details of how this works are given in section
&<<SECTverifyCSA>>&.
-.new
.vitem &*verify&~=&~header_names_ascii*&
.cindex "&%verify%& ACL condition"
.cindex "&ACL;" "verifying header names only ASCII"
Exim itself will handle headers with non-ASCII characters, but it can cause
problems for downstream applications, so this option will allow their
detection and rejection in the DATA ACL's.
-.wen
.vitem &*verify&~=&~header_sender/*&<&'options'&>
.cindex "&%verify%& ACL condition"
received, that is, in an ACL specified by &%acl_smtp_data%& or
&%acl_not_smtp%&. It checks the syntax of all header lines that can contain
lists of addresses (&'Sender:'&, &'From:'&, &'Reply-To:'&, &'To:'&, &'Cc:'&,
-and &'Bcc:'&). Unqualified addresses (local parts without domains) are
+and &'Bcc:'&), returning true if there are no problems.
+Unqualified addresses (local parts without domains) are
permitted only in locally generated messages and from hosts that match
&%sender_unqualified_hosts%& or &%recipient_unqualified_hosts%&, as
appropriate.
address, and in that case, the subsequent value of &$address_data$& is the
value for the child address.
-.vitem &*verify&~=&~reverse_host_lookup*&
+.vitem &*verify&~=&~reverse_host_lookup/*&<&'options'&>
.cindex "&%verify%& ACL condition"
.cindex "&ACL;" "verifying host reverse lookup"
.cindex "host" "verifying reverse lookup"
one of its aliases, does, when it is itself looked up in the DNS, yield the
original IP address.
+There is one possible option, &`defer_ok`&. If this is present and a
+DNS operation returns a temporary error, the verify condition succeeds.
+
If this condition is used for a locally generated message (that is, when there
is no client host involved), it always succeeds.
warn message = X-Warn: sending host is on dialups list
dnslists = dialups.mail-abuse.org
.endd
-DNS list lookups are cached by Exim for the duration of the SMTP session,
+.cindex cacheing "of dns lookup"
+.cindex DNS TTL
+DNS list lookups are cached by Exim for the duration of the SMTP session
+.new
+(but limited by the DNS return TTL value),
+.wen
so a lookup based on the IP address is done at most once for any incoming
-connection. Exim does not share information between multiple incoming
+connection (assuming long-enough TTL).
+Exim does not share information between multiple incoming
connections (but your local name server cache should be active).
accepted. It can be used in the &%acl_smtp_rcpt%&, &%acl_smtp_predata%&,
&%acl_smtp_mime%&, &%acl_smtp_data%&, or &%acl_smtp_rcpt%& ACLs. In
&%acl_smtp_rcpt%& the rate is updated one recipient at a time; in the other
-ACLs the rate is updated with the total recipient count in one go. Note that
+ACLs the rate is updated with the total (accepted) recipient count in one go. Note that
in either case the rate limiting engine will see a message with many
recipients as a large high-speed burst.
specialized interfaces for &"daemon"& type virus scanners, which are resident
in memory and thus are much faster.
+A timeout of 2 minutes is applied to a scanner call (by default);
+if it expires then a defer action is taken.
.oindex "&%av_scanner%&"
-You can set the &%av_scanner%& option in first part of the Exim configuration
-file to specify which scanner to use, together with any additional options that
+You can set the &%av_scanner%& option in the main part of the configuration
+to specify which scanner to use, together with any additional options that
are needed. The basic syntax is as follows:
.display
&`av_scanner = <`&&'scanner-type'&&`>:<`&&'option1'&&`>:<`&&'option2'&&`>:[...]`&
The following scanner types are supported in this release:
.vlist
+.vitem &%avast%&
+.cindex "virus scanners" "avast"
+This is the scanner daemon of Avast. It has been tested with Avast Core
+Security (currently at version 1.1.7).
+You can get a trial version at &url(http://www.avast.com) or for Linux
+at &url(http://www.avast.com/linux-server-antivirus).
+This scanner type takes one option,
+which can be either a full path to a UNIX socket,
+or host and port specifiers separated by white space.
+The host may be a name or an IP address; the port is either a
+single number or a pair of numbers with a dash between.
+Any further options are given, on separate lines,
+to the daemon as options before the main scan command.
+For example:
+.code
+av_scanner = avast:/var/run/avast/scan.sock:FLAGS -fullfiles:SENSITIVITY -pup
+av_scanner = avast:192.168.2.22 5036
+.endd
+If you omit the argument, the default path
+&_/var/run/avast/scan.sock_&
+is used.
+If you use a remote host,
+you need to make Exim's spool directory available to it,
+as the scanner is passed a file path, not file contents.
+For information about available commands and their options you may use
+.code
+$ socat UNIX:/var/run/avast/scan.sock STDIO:
+ FLAGS
+ SENSITIVITY
+ PACK
+.endd
+
+
.vitem &%aveserver%&
.cindex "virus scanners" "Kaspersky"
This is the scanner daemon of Kaspersky Version 5. You can get a trial version
This daemon-type scanner is GPL and free. You can get it at
&url(http://www.clamav.net/). Some older versions of clamd do not seem to
unpack MIME containers, so it used to be recommended to unpack MIME attachments
-in the MIME ACL. This no longer believed to be necessary. One option is
-required: either the path and name of a UNIX socket file, or a hostname or IP
-number, and a port, separated by space, as in the second of these examples:
+in the MIME ACL. This is no longer believed to be necessary.
+
+The options are a list of server specifiers, which may be
+a UNIX socket specification,
+a TCP socket specification,
+or a (global) option.
+
+A socket specification consists of a space-separated list.
+For a Unix socket the first element is a full path for the socket,
+for a TCP socket the first element is the IP address
+and the second a port number,
+Any further elements are per-server (non-global) options.
+These per-server options are supported:
+.code
+retry=<timespec> Retry on connect fail
+.endd
+
+The &`retry`& option specifies a time after which a single retry for
+a failed connect is made. The default is to not retry.
+
+If a Unix socket file is specified, only one server is supported.
+
+Examples:
.code
av_scanner = clamd:/opt/clamd/socket
av_scanner = clamd:192.0.2.3 1234
av_scanner = clamd:192.0.2.3 1234:local
+av_scanner = clamd:192.0.2.3 1234 retry=10s
av_scanner = clamd:192.0.2.3 1234 : 192.0.2.4 1234
.endd
-If the value of av_scanner points to a UNIX socket file or contains the local
-keyword, then the ClamAV interface will pass a filename containing the data
+If the value of av_scanner points to a UNIX socket file or contains the
+&`local`&
+option, then the ClamAV interface will pass a filename containing the data
to be scanned, which will should normally result in less I/O happening and be
more efficient. Normally in the TCP case, the data is streamed to ClamAV as
Exim does not assume that there is a common filesystem with the remote host.
.endd
.vitem &%drweb%&
.cindex "virus scanners" "DrWeb"
-The DrWeb daemon scanner (&url(http://www.sald.com/)) interface takes one
-argument, either a full path to a UNIX socket, or an IP address and port
-separated by white space, as in these examples:
+The DrWeb daemon scanner (&url(http://www.sald.com/)) interface
+takes one option,
+either a full path to a UNIX socket,
+or host and port specifiers separated by white space.
+The host may be a name or an IP address; the port is either a
+single number or a pair of numbers with a dash between.
+For example:
.code
av_scanner = drweb:/var/run/drwebd.sock
av_scanner = drweb:192.168.2.20 31337
If you omit the argument, the default path &_/usr/local/drweb/run/drwebd.sock_&
is used. Thanks to Alex Miller for contributing the code for this scanner.
+.vitem &%f-protd%&
+.cindex "virus scanners" "f-protd"
+The f-protd scanner is accessed via HTTP over TCP.
+One argument is taken, being a space-separated hostname and port number
+(or port-range).
+For example:
+.code
+av_scanner = f-protd:localhost 10200-10204
+.endd
+If you omit the argument, the default values show above are used.
+
.vitem &%fsecure%&
.cindex "virus scanners" "F-Secure"
The F-Secure daemon scanner (&url(http://www.f-secure.com)) takes one
This is a general-purpose way of talking to simple scanner daemons
running on the local machine.
There are four options:
-an address (which may be an IP addres and port, or the path of a Unix socket),
+an address (which may be an IP address and port, or the path of a Unix socket),
a commandline to send (may include a single %s which will be replaced with
the path to the mail file to be scanned),
an RE to trigger on from the returned data,
message.
The &%malware%& condition takes a right-hand argument that is expanded before
-use. It can then be one of
+use and taken as a list, slash-separated by default.
+The first element can then be one of
.ilist
&"true"&, &"*"&, or &"1"&, in which case the message is scanned for viruses.
A regular expression, in which case the message is scanned for viruses. The
condition succeeds if a virus is found and its name matches the regular
expression. This allows you to take special actions on certain types of virus.
+Note that &"/"& characters in the RE must be doubled due to the list-processing,
+unless the separator is changed (in the usual way).
.endlist
-You can append &`/defer_ok`& to the &%malware%& condition to accept messages
-even if there is a problem with the virus scanner. Otherwise, such a problem
-causes the ACL to defer.
+You can append a &`defer_ok`& element to the &%malware%& argument list to accept
+messages even if there is a problem with the virus scanner.
+Otherwise, such a problem causes the ACL to defer.
+
+You can append a &`tmo=<val>`& element to the &%malware%& argument list to
+specify a non-default timeout. The default is two minutes.
+For example:
+.code
+malware = * / defer_ok / tmo=10s
+.endd
+A timeout causes the ACL to defer.
+
+.vindex "&$callout_address$&"
+When a connection is made to the scanner the expansion variable &$callout_address$&
+is set to record the actual address used.
.vindex "&$malware_name$&"
When a virus is found, the condition sets up an expansion variable called
.endd
-.section "Scanning with SpamAssassin" "SECTscanspamass"
+.section "Scanning with SpamAssassin and Rspamd" "SECTscanspamass"
.cindex "content scanning" "for spam"
.cindex "spam scanning"
.cindex "SpamAssassin"
+.cindex "Rspamd"
The &%spam%& ACL condition calls SpamAssassin's &%spamd%& daemon to get a spam
-score and a report for the message. You can get SpamAssassin at
-&url(http://www.spamassassin.org), or, if you have a working Perl
-installation, you can use CPAN by running:
+score and a report for the message.
+Support is also provided for Rspamd.
+
+For more information about installation and configuration of SpamAssassin or
+Rspamd refer to their respective websites at
+&url(http://spamassassin.apache.org) and &url(http://www.rspamd.com)
+
+SpamAssassin can be installed with CPAN by running:
.code
perl -MCPAN -e 'install Mail::SpamAssassin'
.endd
nicely, however.
.oindex "&%spamd_address%&"
-After having installed and configured SpamAssassin, start the &%spamd%& daemon.
-By default, it listens on 127.0.0.1, TCP port 783. If you use another host or
-port for &%spamd%&, you must set the &%spamd_address%& option in the global
-part of the Exim configuration as follows (example):
+By default, SpamAssassin listens on 127.0.0.1, TCP port 783 and if you
+intend to use an instance running on the local host you do not need to set
+&%spamd_address%&. If you intend to use another host or port for SpamAssassin,
+you must set the &%spamd_address%& option in the global part of the Exim
+configuration as follows (example):
.code
spamd_address = 192.168.99.45 387
.endd
-You do not need to set this option if you use the default. As of version 2.60,
-&%spamd%& also supports communication over UNIX sockets. If you want to use
-these, supply &%spamd_address%& with an absolute file name instead of a
-address/port pair:
+
+To use Rspamd (which by default listens on all local addresses
+on TCP port 11333)
+you should add &%variant=rspamd%& after the address/port pair, for example:
+.code
+spamd_address = 127.0.0.1 11333 variant=rspamd
+.endd
+
+As of version 2.60, &%SpamAssassin%& also supports communication over UNIX
+sockets. If you want to us these, supply &%spamd_address%& with an absolute
+file name instead of an address/port pair:
.code
spamd_address = /var/run/spamd_socket
.endd
You can have multiple &%spamd%& servers to improve scalability. These can
reside on other hardware reachable over the network. To specify multiple
&%spamd%& servers, put multiple address/port pairs in the &%spamd_address%&
-option, separated with colons:
+option, separated with colons (the separator can be changed in the usual way):
.code
spamd_address = 192.168.2.10 783 : \
192.168.2.11 783 : \
192.168.2.12 783
.endd
-Up to 32 &%spamd%& servers are supported. The servers are queried in a random
-fashion. When a server fails to respond to the connection attempt, all other
+Up to 32 &%spamd%& servers are supported.
+When a server fails to respond to the connection attempt, all other
servers are tried until one succeeds. If no server responds, the &%spam%&
condition defers.
-&*Warning*&: It is not possible to use the UNIX socket connection method with
-multiple &%spamd%& servers.
+Unix and TCP socket specifications may be mixed in any order.
+Each element of the list is a list itself, space-separated by default
+and changeable in the usual way.
+
+For TCP socket specifications a host name or IP (v4 or v6, but
+subject to list-separator quoting rules) address can be used,
+and the port can be one or a dash-separated pair.
+In the latter case, the range is tried in strict order.
+
+Elements after the first for Unix sockets, or second for TCP socket,
+are options.
+The supported options are:
+.code
+pri=<priority> Selection priority
+weight=<value> Selection bias
+time=<start>-<end> Use only between these times of day
+retry=<timespec> Retry on connect fail
+tmo=<timespec> Connection time limit
+variant=rspamd Use Rspamd rather than SpamAssassin protocol
+.endd
+
+The &`pri`& option specifies a priority for the server within the list,
+higher values being tried first.
+The default priority is 1.
+
+The &`weight`& option specifies a selection bias.
+Within a priority set
+servers are queried in a random fashion, weighted by this value.
+The default value for selection bias is 1.
+
+Time specifications for the &`time`& option are <hour>.<minute>.<second>
+in the local time zone; each element being one or more digits.
+Either the seconds or both minutes and seconds, plus the leading &`.`&
+characters, may be omitted and will be taken as zero.
+
+Timeout specifications for the &`retry`& and &`tmo`& options
+are the usual Exim time interval standard, e.g. &`20s`& or &`1m`&.
+
+The &`tmo`& option specifies an overall timeout for communication.
+The default value is two minutes.
+
+The &`retry`& option specifies a time after which a single retry for
+a failed connect is made.
+The default is to not retry.
The &%spamd_address%& variable is expanded before use if it starts with
a dollar sign. In this case, the expansion may return a string that is
used as the list so that multiple spamd servers can be the result of an
expansion.
+.vindex "&$callout_address$&"
+When a connection is made to the server the expansion variable &$callout_address$&
+is set to record the actual address used.
+
.section "Calling SpamAssassin from an Exim ACL" "SECID206"
Here is a simple example of the use of the &%spam%& condition in a DATA ACL:
.code
relevant if you have set up multiple SpamAssassin profiles. If you do not want
to scan using a specific profile, but rather use the SpamAssassin system-wide
default profile, you can scan for an unknown name, or simply use &"nobody"&.
-However, you must put something on the right-hand side.
+Rspamd does not use this setting. However, you must put something on the
+right-hand side.
The name allows you to use per-domain or per-user antispam profiles in
principle, but this is not straightforward in practice, because a message may
have multiple recipients, not necessarily all in the same domain. Because the
-&%spam%& condition has to be called from a DATA ACL in order to be able to
+&%spam%& condition has to be called from a DATA-time ACL in order to be able to
read the contents of the message, the variables &$local_part$& and &$domain$&
are not set.
+Careful enforcement of single-recipient messages
+(e.g. by responding with defer in the recipient ACL for all recipients
+after the first),
+or the use of PRDR,
+.cindex "PRDR" "use for per-user SpamAssassin profiles"
+are needed to use this feature.
The right-hand side of the &%spam%& condition is expanded before being used, so
you can put lookups or conditions there. When the right-hand side evaluates to
.cindex "spam scanning" "returned variables"
When the &%spam%& condition is run, it sets up a number of expansion
-variables. These variables are saved with the received message, thus they are
+variables.
+Except for &$spam_report$&,
+these variables are saved with the received message so are
available for use at delivery time.
.vlist
A string consisting of a number of &"+"& or &"-"& characters, representing the
integer part of the spam score value. A spam score of 4.4 would have a
&$spam_bar$& value of &"++++"&. This is useful for inclusion in warning
-headers, since MUAs can match on such strings.
+headers, since MUAs can match on such strings. The maximum length of the
+spam bar is 50 characters.
.vitem &$spam_report$&
A multiline text table, containing the full SpamAssassin report for the
message. Useful for inclusion in headers or reject messages.
+This variable is only usable in a DATA-time ACL.
+
+.vitem &$spam_action$&
+For SpamAssassin either 'reject' or 'no action' depending on the
+spam score versus threshold.
+For Rspamd, the recommended action.
+
.endlist
The &%spam%& condition caches its results unless expansion in
This is perhaps the most important of the MIME variables. It contains a
proposed filename for an attachment, if one was found in either the
&'Content-Type:'& or &'Content-Disposition:'& headers. The filename will be
-RFC2047 decoded, but no additional sanity checks are done. If no filename was
+RFC2047
+or RFC2231
+decoded, but no additional sanity checks are done.
+ If no filename was
found, this variable contains the empty string.
.vitem &$mime_is_coverletter$&
The conditions returns true if any one of the regular expressions matches. The
&$regex_match_string$& expansion variable is then set up and contains the
matching regular expression.
+The expansion variables &$regex1$& &$regex2$& etc
+are set to any substrings captured by the regular expression.
&*Warning*&: With large messages, these conditions can be fairly
CPU-intensive.
Multiple &%headers_remove%& options for a single router or transport can be
specified; the arguments will append to a single header-names list.
Each item is separately expanded.
+Note that colons in complex expansions which are used to
+form all or part of a &%headers_remove%& list
+will act as list separators.
When &%headers_add%& or &%headers_remove%& is specified on a router,
items are expanded at routing time,
The third item is used to introduce any text from pipe transports that is to be
returned to the sender. It is omitted if there is no such text.
.next
-The fourth item is used to introduce the copy of the message that is returned
-as part of the error report.
-.next
-The fifth item is added after the fourth one if the returned message is
-truncated because it is bigger than &%return_size_limit%&.
-.next
-The sixth item is added after the copy of the original message.
+The fourth, fifth and sixth items will be ignored and may be empty.
+The fields exist for back-compatibility
.endlist
The default state (&%bounce_message_file%& unset) is equivalent to the
.code
log_file_path = $spool_directory/log/%slog
.endd
-If you do not specify anything at build time or run time, that is where the
-logs are written.
+If you do not specify anything at build time or run time,
+or if you unset the option at run time (i.e. &`log_file_path = `&),
+that is where the logs are written.
A log file path may also contain &`%D`& or &`%M`& if datestamped log file names
are in use &-- see section &<<SECTdatlogfil>>& below.
session was encrypted, there is an additional X field that records the cipher
suite that was used.
+.cindex log protocol
The protocol is set to &"esmtpsa"& or &"esmtpa"& for messages received from
hosts that have authenticated themselves using the SMTP AUTH command. The first
value is used when the SMTP connection was encrypted (&"secure"&). In this case
.cindex "log" "delivery line"
The format of the single-line entry in the main log that is written for every
delivery is shown in one of the examples below, for local and remote
-deliveries, respectively. Each example has been split into two lines in order
+deliveries, respectively. Each example has been split into multiple lines in order
to fit it on the page:
.code
2002-10-31 08:59:13 16ZCW1-0005MB-00 => marv
&`id `& message id for incoming message
&`P `& on &`<=`& lines: protocol used
&` `& on &`=>`& and &`**`& lines: return path
+&`PRX `& on &'<='& and&`=>`& lines: proxy address
&`QT `& on &`=>`& lines: time spent on queue so far
&` `& on &"Completed"& lines: time spent on queue
&`R `& on &`<=`& lines: reference for local bounce
&`*etrn `& ETRN commands
&`*host_lookup_failed `& as it says
&` ident_timeout `& timeout for ident connection
-&` incoming_interface `& incoming interface on <= lines
-&` incoming_port `& incoming port on <= lines
+&` incoming_interface `& local interface on <= and => lines
+&` incoming_port `& remote port on <= lines
&`*lost_incoming_connection `& as it says (includes timeouts)
+.new
+&` outgoing_interface `& local interface on => lines
+.wen
&` outgoing_port `& add remote port to => lines
&`*queue_run `& start and end queue runs
&` queue_time `& time on queue for one recipient
&` queue_time_overall `& time on queue for whole message
&` pid `& Exim process id
+.new
+&` proxy `& proxy address on <= and => lines
+.wen
&` received_recipients `& recipients on <= lines
&` received_sender `& sender on <= lines
&`*rejected_header `& header contents on reject log
&`*size_reject `& rejection because too big
&`*skip_delivery `& delivery skipped in a queue run
&`*smtp_confirmation `& SMTP confirmation on => lines
-&` smtp_connection `& SMTP connections
+&` smtp_connection `& incoming SMTP connections
&` smtp_incomplete_transaction`& incomplete SMTP transactions
&` smtp_mailauth `& AUTH argument to MAIL commands
&` smtp_no_mail `& session with no MAIL commands
&` smtp_protocol_error `& SMTP protocol errors
&` smtp_syntax_error `& SMTP syntax errors
&` subject `& contents of &'Subject:'& on <= lines
-&` tls_certificate_verified `& certificate verification status
+&`*tls_certificate_verified `& certificate verification status
&`*tls_cipher `& TLS cipher suite on <= and => lines
&` tls_peerdn `& TLS peer DN on <= and => lines
&` tls_sni `& TLS SNI on <= lines
&` all `& all of the above
.endd
+See also the &%slow_lookup_log%& main configuration option,
+section &<<SECID99>>&
+
More details on each of these items follows:
.ilist
client's ident port times out.
.next
.cindex "log" "incoming interface"
+.cindex "log" "local interface"
+.cindex "log" "local address and port"
+.cindex "TCP/IP" "logging local address and port"
.cindex "interface" "logging"
&%incoming_interface%&: The interface on which a message was received is added
to the &"<="& line as an IP address in square brackets, tagged by I= and
followed by a colon and the port number. The local interface and port are also
-added to other SMTP log lines, for example &"SMTP connection from"&, and to
-rejection lines.
+added to other SMTP log lines, for example &"SMTP connection from"&, to
+rejection lines, and (despite the name) to outgoing &"=>"& and &"->"& lines.
+.new
+The latter can be disabled by turning off the &%outgoing_interface%& option.
+.wen
+.next
+.new
+.cindex log "incoming proxy address"
+.cindex proxy "logging proxy address"
+.cindex "TCP/IP" "logging proxy address"
+&%proxy%&: The internal (closest to the system running Exim) IP address
+of the proxy, tagged by PRX=, on the &"<="& line for a message accepted
+on a proxied connection
+or the &"=>"& line for a message delivered on a proxied connection..
+See &<<SECTproxyInbound>>& for more information.
+.wen
.next
.cindex "log" "incoming remote port"
.cindex "port" "logging remote"
&%lost_incoming_connection%&: A log line is written when an incoming SMTP
connection is unexpectedly dropped.
.next
+.cindex "log" "outgoing interface"
+.cindex "log" "local interface"
+.cindex "log" "local address and port"
+.cindex "TCP/IP" "logging local address and port"
+.cindex "interface" "logging"
+.new
+&%outgoing_interface%&: If &%incoming_interface%& is turned on, then the
+interface on which a message was sent is added to delivery lines as an I= tag
+followed by IP address in square brackets. You can disable this by turning
+off the &%outgoing_interface%& option.
+.wen
+.next
.cindex "log" "outgoing remote port"
.cindex "port" "logging outgoint remote"
.cindex "TCP/IP" "logging ougtoing remote port"
&%outgoing_port%&: The remote port number is added to delivery log lines (those
-containing => tags) following the IP address. This option is not included in
-the default setting, because for most ordinary configurations, the remote port
-number is always 25 (the SMTP port).
+containing => tags) following the IP address.
+.new
+The local port is also added if &%incoming_interface%& and
+&%outgoing_interface%& are both enabled.
+.wen
+This option is not included in the default setting, because for most ordinary
+configurations, the remote port number is always 25 (the SMTP port), and the
+local port is a random ephemeral port.
.next
.cindex "log" "process ids in"
.cindex "pid (process id)" "in log lines"
.next
.cindex "log" "SMTP connections"
.cindex "SMTP" "logging connections"
-&%smtp_connection%&: A log line is written whenever an SMTP connection is
+&%smtp_connection%&: A log line is written whenever an incoming SMTP connection is
established or closed, unless the connection is from a host that matches
&%hosts_connection_nolog%&. (In contrast, &%lost_incoming_connection%& applies
only when the closure is unexpected.) This applies to connections from local
shows that the client issued QUIT straight after EHLO. If there were fewer
than 20 commands, they are all listed. If there were more than 20 commands,
the last 20 are listed, preceded by &"..."&. However, with the default
-setting of 10 for &%smtp_accep_max_nonmail%&, the connection will in any case
+setting of 10 for &%smtp_accept_max_nonmail%&, the connection will in any case
have been aborted before 20 non-mail commands are processed.
.next
&%smtp_mailauth%&: A third subfield with the authenticated sender,
.code
exim -bp
.endd
-.new
The &*-C*& option is used to specify an alternate &_exim.conf_& which might
contain alternate exim configuration the queue management might be using.
-.wen
-to obtain a queue listing, and then greps the output to select messages
+to obtain a queue listing, and then greps the output to select messages
that match given criteria. The following selection options are available:
.vlist
exiqgrep -f '^<>$'
.endd
.vitem &*-r*&&~<&'regex'&>
-Match a recipient address using a case-insensitve search. The field that is
+Match a recipient address using a case-insensitive search. The field that is
tested is not enclosed in angle brackets.
.vitem &*-s*&&~<&'regex'&>
If a matching log line is not associated with a specific message, it is
included in &'exigrep'&'s output without any additional lines. The usage is:
.display
-&`exigrep [-t<`&&'n'&&`>] [-I] [-l] [-v] <`&&'pattern'&&`> [<`&&'log file'&&`>] ...`&
+&`exigrep [-t<`&&'n'&&`>] [-I] [-l] [-M] [-v] <`&&'pattern'&&`> [<`&&'log file'&&`>] ...`&
.endd
If no log file names are given on the command line, the standard input is read.
The &%-v%& option inverts the matching condition. That is, a line is selected
if it does &'not'& match the pattern.
+The &%-M%& options means &"related messages"&. &'exigrep'& will show messages
+that are generated as a result/response to a message that &'exigrep'& matched
+normally.
+
+Example of &%-M%&:
+user_a sends a message to user_b, which generates a bounce back to user_b. If
+&'exigrep'& is used to search for &"user_a"&, only the first message will be
+displayed. But if &'exigrep'& is used to search for &"user_b"&, the first and
+the second (bounce) message will be displayed. Using &%-M%& with &'exigrep'&
+when searching for &"user_a"& will show both messages since the bounce is
+&"related"& to or a &"result"& of the first message that was found by the
+search term.
+
If the location of a &'zcat'& command is known from the definition of
ZCAT_COMMAND in &_Local/Makefile_&, &'exigrep'& automatically passes any file
whose name ends in COMPRESS_SUFFIX through &'zcat'& as it searches it.
+If the ZCAT_COMMAND is not executable, &'exigrep'& tries to use
+autodetection of some well known compression extensions.
.section "Selecting messages by various criteria (exipick)" "SECTexipick"
.next
Serializing delivery to a specific host (when &%serialize_hosts%& is set in an
&(smtp)& transport)
+.next
+Limiting the concurrency of specific transports (when &%max_parallel%& is set
+in a transport)
.endlist
Administrators who use embedded Perl are advised to explore how Perl's
taint checking might apply to their usage.
.next
-Use of &%${expand...}%& is somewhat analagous to shell's eval builtin and
+Use of &%${expand...}%& is somewhat analogous to shell's eval builtin and
administrators are well advised to view its use with suspicion, in case (for
instance) it allows a local-part to contain embedded Exim directives.
.next
&%acl_smtp_dkim%& ACL. By default, this ACL is called once for each
syntactically(!) correct signature in the incoming message.
A missing ACL definition defaults to accept.
-If any ACL call does not acccept, the message is not accepted.
+If any ACL call does not accept, the message is not accepted.
If a cutthrough delivery was in progress for the message it is
summarily dropped (having wasted the transmission effort).
&%pass%&: The signature passed verification. It is valid.
.endlist
.vitem &%$dkim_verify_reason%&
-A string giving a litte bit more detail when &%$dkim_verify_status%& is either
+A string giving a little bit more detail when &%$dkim_verify_status%& is either
"fail" or "invalid". One of
.ilist
&%pubkey_unavailable%& (when &%$dkim_verify_status%&="invalid"): The public
in the key record.
.vitem &%$dkim_key_notes%&
Notes from the key record (tag n=).
+.vitem &%$dkim_key_length%&
+Number of bits in the key.
.endlist
In addition, two ACL conditions are provided:
. ////////////////////////////////////////////////////////////////////////////
. ////////////////////////////////////////////////////////////////////////////
+.chapter "Proxies" "CHAPproxies" &&&
+ "Proxy support"
+.cindex "proxy support"
+.cindex "proxy" "access via"
+
+.new
+A proxy is an intermediate system through which communication is passed.
+Proxies may provide a security, availability or load-distribution function.
+
+
+.section "Inbound proxies" SECTproxyInbound
+.cindex proxy inbound
+.cindex proxy "server side"
+.cindex proxy "Proxy protocol"
+.cindex "Proxy protocol" proxy
+
+Exim has support for receiving inbound SMTP connections via a proxy
+that uses &"Proxy Protocol"& to speak to it.
+To include this support, include &"SUPPORT_PROXY=yes"&
+in Local/Makefile.
+
+It was built on specifications from:
+http://haproxy.1wt.eu/download/1.5/doc/proxy-protocol.txt
+That URL was revised in May 2014 to version 2 spec:
+http://git.1wt.eu/web?p=haproxy.git;a=commitdiff;h=afb768340c9d7e50d8e
+
+The purpose of this facility is so that an application load balancer,
+such as HAProxy, can sit in front of several Exim servers
+to distribute load.
+Exim uses the local protocol communication with the proxy to obtain
+the remote SMTP system IP address and port information.
+There is no logging if a host passes or
+fails Proxy Protocol negotiation, but it can easily be determined and
+recorded in an ACL (example is below).
+
+Use of a proxy is enabled by setting the &%hosts_proxy%&
+main configuration option to a hostlist; connections from these
+hosts will use Proxy Protocol.
+
+The following expansion variables are usable
+(&"internal"& and &"external"& here refer to the interfaces
+of the proxy):
+.display
+&'proxy_host_address '& internal IP address of the proxy
+&'proxy_host_port '& internal TCP port of the proxy
+&'proxy_target_address '& external IP address of the proxy
+&'proxy_target_port '& external TCP port of the proxy
+&'proxy_session '& boolean: SMTP connection via proxy
+.endd
+If &$proxy_session$& is set but &$proxy_host_address$& is empty
+there was a protocol error.
+
+Since the real connections are all coming from the proxy, and the
+per host connection tracking is done before Proxy Protocol is
+evaluated, &%smtp_accept_max_per_host%& must be set high enough to
+handle all of the parallel volume you expect per inbound proxy.
+With the option set so high, you lose the ability
+to protect your server from many connections from one IP.
+In order to prevent your server from overload, you
+need to add a per connection ratelimit to your connect ACL.
+A possible solution is:
+.display
+ # Set max number of connections per host
+ LIMIT = 5
+ # Or do some kind of IP lookup in a flat file or database
+ # LIMIT = ${lookup{$sender_host_address}iplsearch{/etc/exim/proxy_limits}}
+
+ defer message = Too many connections from this IP right now
+ ratelimit = LIMIT / 5s / per_conn / strict
+.endd
+
+
+
+.section "Outbound proxies" SECTproxySOCKS
+.cindex proxy outbound
+.cindex proxy "client side"
+.cindex proxy SOCKS
+.cindex SOCKS proxy
+Exim has support for sending outbound SMTP via a proxy
+using a protocol called SOCKS5 (defined by RFC1928).
+The support can be optionally included by defining SUPPORT_SOCKS=yes in
+Local/Makefile.
+
+Use of a proxy is enabled by setting the &%socks_proxy%& option
+on an smtp transport.
+The option value is expanded and should then be a list
+(colon-separated by default) of proxy specifiers.
+Each proxy specifier is a list
+(space-separated by default) where the initial element
+is an IP address and any subsequent elements are options.
+
+Options are a string <name>=<value>.
+The list of options is in the following table:
+.display
+&'auth '& authentication method
+&'name '& authentication username
+&'pass '& authentication password
+&'port '& tcp port
+&'tmo '& connection timeout
+&'pri '& priority
+&'weight '& selection bias
+.endd
+
+More details on each of these options follows:
+
+.ilist
+.cindex authentication "to proxy"
+.cindex proxy authentication
+&%auth%&: Either &"none"& (default) or &"name"&.
+Using &"name"& selects username/password authentication per RFC 1929
+for access to the proxy.
+Default is &"none"&.
+.next
+&%name%&: sets the username for the &"name"& authentication method.
+Default is empty.
+.next
+&%pass%&: sets the password for the &"name"& authentication method.
+Default is empty.
+.next
+&%port%&: the TCP port number to use for the connection to the proxy.
+Default is 1080.
+.next
+&%tmo%&: sets a connection timeout in seconds for this proxy.
+Default is 5.
+.next
+&%pri%&: specifies a priority for the proxy within the list,
+higher values being tried first.
+The default priority is 1.
+.next
+&%weight%&: specifies a selection bias.
+Within a priority set servers are queried in a random fashion,
+weighted by this value.
+The default value for selection bias is 1.
+.endlist
+
+Proxies from the list are tried according to their priority
+and weight settings until one responds. The timeout for the
+overall connection applies to the set of proxied attempts.
+
+.section Logging SECTproxyLog
+To log the (local) IP of a proxy in the incoming or delivery logline,
+add &"+proxy"& to the &%log_selector%& option.
+This will add a component tagged with &"PRX="& to the line.
+.wen
+
+. ////////////////////////////////////////////////////////////////////////////
+. ////////////////////////////////////////////////////////////////////////////
+
+.chapter "Internationalisation" "CHAPi18n" &&&
+ "Internationalisation""
+.cindex internationalisation "email address"
+.cindex EAI
+.cindex i18n
+.cindex UTF-8 "mail name handling"
+
+.new
+Exim has support for Internationalised mail names.
+To include this it must be built with SUPPORT_I18N and the libidn library.
+Standards supported are RFCs 2060, 5890, 6530 and 6533.
+
+.section "MTA operations" SECTi18nMTA
+.cindex SMTPUTF8 "ESMTP option"
+The main configuration option &%smtputf8_advertise_hosts%& specifies
+a host list. If this matches the sending host and
+accept_8bitmime is true (the default) then the ESMTP option
+SMTPUTF8 will be advertised.
+
+If the sender specifies the SMTPUTF8 option on a MAIL command
+international handling for the message is enabled and
+the expansion variable &$message_smtputf8$& will have value TRUE.
+
+The option &%allow_utf8_domains%& is set to true for this
+message. All DNS lookups are converted to a-label form
+whatever the setting of &%allow_utf8_domains%&
+when Exim is built with SUPPORT_I18N.
+
+Both localparts and domain are maintained as the original
+UTF-8 form internally; any comparison or regular-expression use will
+require appropriate care. Filenames created, eg. by
+the appendfile transport, will have UTF-8 names.
+
+Helo names sent by the smtp transport will have any UTF-8
+components expanded to a-label form,
+and any certificate name checks will be done using the a-label
+form of the name.
+
+.cindex log protocol
+.cindex SMTPUTF8 logging
+Log lines and Received-by: header lines will acquire a "utf8"
+prefix on the protocol element, eg. utf8esmtp.
+
+The following expansion operator can be used:
+.code
+${utf8_domain_to_alabel:str}
+${utf8_domain_from_alabel:str}
+${utf8_localpart_to_alabel:str}
+${utf8_localpart_from_alabel:str}
+.endd
+
+ACLs may use the following modifier:
+.display
+control = utf8_downconvert
+control = utf8_downconvert/<value>
+.endd
+This sets a flag requiring that addresses are converted to
+a-label form before smtp delivery, for use in a
+Message Submission Agent context.
+If a value is appended it may be:
+.display
+&`1 `& (default) mandatory downconversion
+&`0 `& no downconversion
+&`-1 `& if SMTPUTF8 not supported by destination host
+.endd
+
+If mua_wrapper is set, the utf8_downconvert control
+is initially set to -1.
+
+
+There is no explicit support for VRFY and EXPN.
+Configurations supporting these should inspect
+&$smtp_command_argument$& for an SMTPUTF8 argument.
+
+There is no support for LMTP on Unix sockets.
+Using the "lmtp" protocol option on an smtp transport,
+for LMTP over TCP, should work as expected.
+
+There is no support for DSN unitext handling,
+and no provision for converting logging from or to UTF-8.
+
+
+
+.section "MDA operations" SECTi18nMDA
+To aid in constructing names suitable for IMAP folders
+the following expansion operator can be used:
+.code
+${imapfolder {<string>} {<sep>} {<specials>}}
+.endd
+
+The string is converted from the charset specified by
+the "headers charset" command (in a filter file)
+or &%headers_charset%& main configuration option (otherwise),
+to the
+modified UTF-7 encoding specified by RFC 2060,
+with the following exception: All occurences of <sep>
+(which has to be a single character)
+are replaced with periods ("."), and all periods and slashes that are not
+<sep> and are not in the <specials> string are BASE64 encoded.
+
+The third argument can be omitted, defaulting to an empty string.
+The second argument can be omitted, defaulting to "/".
+
+This is the encoding used by Courier for Maildir names on disk, and followed
+by many other IMAP servers.
+
+Examples:
+.display
+&`${imapfolder {Foo/Bar}} `& yields &`Foo.Bar`&
+&`${imapfolder {Foo/Bar}{.}{/}} `& yields &`Foo&&AC8-Bar`&
+&`${imapfolder {Räksmörgås}} `& yields &`R&&AOQ-ksm&&APY-rg&&AOU-s`&
+.endd
+
+Note that the source charset setting is vital, and also that characters
+must be representable in UTF-16.
+
+.wen
+
+. ////////////////////////////////////////////////////////////////////////////
+. ////////////////////////////////////////////////////////////////////////////
+
.chapter "Adding new drivers or lookup types" "CHID13" &&&
"Adding drivers or lookups"
.cindex "adding drivers"
git://git.exim.org / users / heiko / exim.git / blobdiff