. Update the Copyright year (only) when changing content.
. /////////////////////////////////////////////////////////////////////////////
-.set previousversion "4.93"
+.set previousversion "4.94"
.include ./local_params
.set ACL "access control lists (ACLs)"
&%local_part_suffix%& is in use, the prefix or suffix is removed from the local
part before this check. If you want to do precondition tests on local parts
that include affixes, you can do so by using a &%condition%& option (see below)
-.new
that uses the variables &$local_part$&, &$local_part_prefix$&,
&$local_part_prefix_v$&, &$local_part_suffix$&
and &$local_part_suffix_v$& as necessary.
-.wen
.next
.vindex "&$local_user_uid$&"
.vindex "&$local_user_gid$&"
by Exim in conjunction with the &%-MC%& option. It signifies that the
remote host supports the ESMTP &_DSN_& extension.
-.new
.vitem &%-MCd%&
.oindex "&%-MCd%&"
This option is not intended for use by external callers. It is used internally
by Exim in conjunction with the &%-d%& option
to pass on an information string on the purpose of the process.
-.wen
.vitem &%-MCG%&&~<&'queue&~name'&>
.oindex "&%-MCG%&"
signals the final completion of the sequence of processes that are passing
messages through the same SMTP connection.
+.new
+.vitem &%-MCq%&&~<&'recipient&~address'&>&~<&'size'&>
+.oindex "&%-MCq%&"
+This option is not intended for use by external callers. It is used internally
+by Exim to implement quota checking for local users.
+.wen
+
.vitem &%-MCS%&
.oindex "&%-MCS%&"
This option is not intended for use by external callers. It is used internally
by Exim in conjunction with the &%-MC%& option, and passes on the fact that the
host to which Exim is connected supports TLS encryption.
+.new
+.vitem &%-MCr%&&~<&'SNI'&> &&&
+ &%-MCs%&&~<&'SNI'&>
+.oindex "&%-MCs%&"
+.oindex "&%-MCr%&"
+These options are not intended for use by external callers. It is used internally
+by Exim in conjunction with the &%-MCt%& option, and passes on the fact that
+a TLS Server Name Indication was sent as part of the channel establishment.
+The argument gives the SNI string.
+The "r" variant indicates a DANE-verified connection.
+.wen
+
.vitem &%-MCt%&&~<&'IP&~address'&>&~<&'port'&>&~<&'cipher'&>
.oindex "&%-MCt%&"
This option is not intended for use by external callers. It is used internally
without &%-bd%&, this is the only way of causing Exim to write a pid file,
because in those cases, the normal pid file is not used.
-.new
.vitem &%-oPX%&
.oindex "&%-oPX%&"
.cindex "pid (process id)" "of daemon"
The daemon uses it when terminating due to a SIGTEM, possibly in
combination with &%-oP%&&~<&'path'&>.
It causes the pid file to be removed.
-.wen
.vitem &%-or%&&~<&'time'&>
.oindex "&%-or%&"
in chapter &<<CHAPinterfaces>>&. When &%-oX%& is used to start a daemon, no pid
file is written unless &%-oP%& is also present to specify a pid filename.
+.new
+.vitem &%-oY%&
+.oindex &%-oY%&
+.cindex "daemon notifier socket"
+This option controls the creation of an inter-process communications endpoint
+by the Exim daemon.
+It is only relevant when the &%-bd%& (start listening daemon) option is also
+given.
+Normally the daemon creates this socket, unless a &%-oX%& and &*no*& &%-oP%&
+option is also present.
+If this option is given then the socket will not be created. This could be
+required if the system is running multiple daemons.
+
+The socket is currently used for
+.ilist
+fast ramp-up of queue runner processes
+.next
+obtaining a current queue size
+.endlist
+.wen
+
.vitem &%-pd%&
.oindex "&%-pd%&"
.cindex "Perl" "starting the interpreter"
every domain. Addresses are routed, local deliveries happen, but no remote
transports are run.
-.new
Performance will be best if the &%queue_run_in_order%& option is false.
If that is so and the &%queue_fast_ramp%& option is true then
in the first phase of the run,
once a threshold number of messages are routed for a given host,
a delivery process is forked in parallel with the rest of the scan.
-.wen
.cindex "hints database" "remembering routing"
The hints database that remembers which messages are waiting for specific hosts
input and output (that is, not using TCP/IP). A number of MUAs operate in this
manner.
.code
-deny message = Restricted characters in address
- domains = +local_domains
+deny domains = +local_domains
local_parts = ^[.] : ^.*[@%!/|]
+ message = Restricted characters in address
-deny message = Restricted characters in address
- domains = !+local_domains
+deny domains = !+local_domains
local_parts = ^[./|] : ^.*[@%!] : ^.*/\\.\\./
+ message = Restricted characters in address
.endd
These statements are concerned with local parts that contain any of the
characters &"@"&, &"%"&, &"!"&, &"/"&, &"|"&, or dots in unusual places.
This statement requires the recipient address to be verified; if verification
fails, the address is rejected.
.code
-# deny message = rejected because $sender_host_address \
+# deny dnslists = black.list.example
+# message = rejected because $sender_host_address \
# is in a black list at $dnslist_domain\n\
# $dnslist_text
-# dnslists = black.list.example
#
# warn dnslists = black.list.example
# add_header = X-Warning: $sender_host_address is in \
This &(appendfile)& transport is used for local delivery to user mailboxes in
traditional BSD mailbox format.
-.new
We prefer to avoid using &$local_part$& directly to define the mailbox filename,
as it is provided by a potential bad actor.
Instead we use &$local_part_data$&,
the result of looking up &$local_part$& in the user database
(done by using &%check_local_user%& in the the router).
-.wen
By default &(appendfile)& runs under the uid and gid of the
local user, which requires the sticky bit to be set on the &_/var/mail_&
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.
+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.
+The key for the lookup is &*implicit*&,
+given by the context in which the list is expanded.
.endlist
String expansions, lists, and lookups interact with each other in such a way
In the second example, the lookup is a single item in a domain list. It causes
Exim to use a lookup to see if the domain that is being processed can be found
-in the file. The file could contains lines like this:
+in the file.
+The file could contains lines like this:
.code
domain1:
domain2:
first &%domains%& setting above generates the second setting, which therefore
causes a second lookup to occur.
+.new
+The lookup type may optionally be followed by a comma
+and a comma-separated list of options.
+Each option is a &"name=value"& pair.
+Whether an option is meaningful depends on the lookup type.
+
+All lookups support the option &"cache=no_rd"&.
+If this is given then the cache that Exim manages for lookup results
+is not checked before doing the lookup.
+The result of the lookup is still written to the cache.
+.wen
+
The rest of this chapter describes the different lookup types that are
available. Any of them can be used in any part of the configuration where a
lookup is permitted.
The &'single-key'& type requires the specification of a file in which to look,
and a single key to search for. The key must be a non-empty string for the
lookup to succeed. The lookup type determines how the file is searched.
-.new
.cindex "tainted data" "single-key lookups"
The file string may not be tainted
-.wen
+
+.cindex "tainted data" "de-tainting"
+All single-key lookups support the option &"ret=key"&.
+If this is given and the lookup
+(either underlying implementation or cached value)
+returns data, the result is replaced with a non-tainted
+version of the lookup key.
+.cindex "tainted data" "de-tainting"
.next
.cindex "query-style lookup" "definition of"
The &'query-style'& type accepts a generalized database query. No particular
.cindex "lookup" "dsearch"
.cindex "dsearch lookup type"
&(dsearch)&: The given file must be an
-.new
absolute
-.wen
directory path; this is searched for an entry
whose name is the key by calling the &[lstat()]& function.
The key may not
contain any forward slash characters.
If &[lstat()]& succeeds then so does the lookup.
-.new
.cindex "tainted data" "dsearch result"
The result is regarded as untainted.
.endd
The default matching is for any entry type, including directories
and symlinks.
-.wen
An example of how this
lookup can be used to support virtual domains is given in section
&*Warning 3*&: Do not use an IPv4-mapped IPv6 address for a key; use the
IPv4, in dotted-quad form. (Exim converts IPv4-mapped IPv6 addresses to this
notation before executing the lookup.)
+
+.new
+One option is supported, "ret=full", to request the return of the entire line
+rather than omitting the key porttion.
+Note however that the key portion will have been de-quoted.
+.wen
+
.next
.cindex lookup json
.cindex json "lookup type"
.cindex "sqlite lookup type"
.cindex "lookup" "sqlite"
&(sqlite)&: The format of the query is
-new
-an optional filename
-.wen
-followed by an SQL statement
-that is passed to an SQLite database. See section &<<SECTsqlite>>&.
+an SQL statement that is passed to an SQLite database. See section &<<SECTsqlite>>&.
.next
&(testdb)&: This is a lookup type that is used for testing Exim. It is
escapes whitespace and backslash characters with a backslash.
.section "Specifying the server in the query" "SECTspeserque"
-.new
For MySQL, PostgreSQL and Redis lookups (but not currently for Oracle and InterBase),
it is possible to specify a list of servers with an individual query. This is
done by appending a comma-separated option to the query type:
.display
-.endd
&`,servers=`&&'server1:server2:server3:...'&
-.wen
+.endd
Each item in the list may take one of two forms:
.olist
If it contains no slashes it is assumed to be just a host name. The appropriate
${lookup pgsql,servers=master/db/name/pw {UPDATE ...} }
.endd
-.new
-An older syntax places the servers speciification before the qury,
+An older syntax places the servers specification before the query,
semicolon separated:
.code
${lookup mysql{servers=master; UPDATE ...} }
The new version avoids potential issues with tainted
arguments in the query, for explicit expansion.
&*Note*&: server specifications in list-style lookups are still problematic.
-.wen
.section "Special MySQL features" "SECID73"
.new
.oindex &%sqlite_dbfile%&
-The preferred way of specifying the file is by using the
-&%sqlite_dbfile%& option, set to
-an absolute path.
+There are two ways of
+specifying the file.
+The first is is by using the &%sqlite_dbfile%& main option.
+The second, which allows separate files for each query,
+is to use an option appended, comma-separated, to the &"sqlite"&
+lookup type word. The option is the word &"file"&, then an equals,
+then the filename.
+The filename in this case cannot contain whitespace or open-brace charachters.
.wen
+
A deprecated method is available, prefixing the query with the filename
separated by white space.
-This means that the path name cannot contain white space.
+This means that
.cindex "tainted data" "sqlite file"
-It also means that the query cannot use any tainted values, as that taints
+the query cannot use any tainted values, as that taints
the entire query including the filename - resulting in a refusal to open
the file.
-.new
+In all the above cases the filename must be an absolute path.
+
Here is a lookup expansion example:
.code
sqlite_dbfile = /some/thing/sqlitedb
domainlist relay_to_domains = sqlite;\
select * from relays where ip='$sender_host_address';
.endd
-.wen
The only character affected by the &%quote_sqlite%& operator is a single
quote, which it doubles.
-.new
.section "Results of list checking" SECTlistresults
The primary result of doing a list check is a truth value.
In some contexts additional information is stored
The detail of the additional information depends on the
type of match and is given below as the &*value*& information.
-.wen
where &'x.y'& does not match. It's best to avoid negation altogether in
referenced lists if you can.
-.new
.cindex "hiding named list values"
.cindex "named lists" "hiding value of"
Some named list definitions may contain sensitive data, for example, passwords for
.code
hide domainlist filter_for_domains = ldap;PASS=secret ldap::/// ...
.endd
-.wen
Named lists may have a performance advantage. When Exim is routing an
possible to use the same configuration file on several different hosts that
differ only in their names.
-.new
The value for a match will be the primary host name.
-.wen
.next
In today's Internet, the use of domain literals is controversial;
see the &%allow_domain_literals%& main option.
-.new
The value for a match will be the string &`@[]`&.
-.wen
.next
domains = <? @mx_any/ignore=<;127.0.0.1;::1 ? \
an.other.domain ? ...
.endd
-.new
The value for a match will be the list element string (starting &`@mx_`&).
-.wen
.next
list item such as &`*key.ex`& matches &'donkey.ex'& as well as
&'cipher.key.ex'&.
-.new
The value for a match will be the list element string (starting with the asterisk).
Additionally, &$0$& will be set to the matched string
and &$1$& to the variable portion which the asterisk matched.
-.wen
.next
.cindex "regular expressions" "in domain list"
it is not to be expanded (unless you really do want to build a regular
expression by expansion, of course).
-.new
The value for a match will be the list element string (starting with the circumflex).
Additionally, &$0$& will be set to the string matching the regular expression,
and &$1$& (onwards) to any submatches identified by parentheses.
-.wen
The value will be untainted.
.next
-.new
If the pattern starts with the name of a lookup type
of either kind (single-key or query-style) it may be
followed by a comma and options,
The options are lookup-type specific and consist of a comma-separated list.
Each item starts with a tag and and equals "=".
-.wen
.next
.cindex "domain list" "matching literal domain name"
.cindex "tainted data" "de-tainting"
Note that this is commonly untainted
(depending on the way the list was created).
+Specifically, explicit text in the configuration file in not tainted.
This is a useful way of obtaining an untainted equivalent to
the domain, for later operations.
+
+However if the list (including one-element lists)
+is created by expanding a variable containing tainted data,
+it is tainted and so will the match value be.
.endlist
.section "Local part lists" "SECTlocparlis"
.cindex "list" "local part list"
.cindex "local part" "list"
+These behave in the same way as domain and host lists, with the following
+changes:
+
Case-sensitivity in local part lists is handled in the same way as for address
lists, as just described. The &"+caseful"& item can be used if required. In a
setting of the &%local_parts%& option in a router with &%caseful_local_part%&
conditions do not expand some of the brace-delimited branches, for security
reasons,
.cindex "tainted data" expansion
+.cindex "tainted data" definition
.cindex expansion "tainted data"
and expansion of data deriving from the sender (&"tainted data"&)
is not permitted.
+.new
+Common ways of obtaining untainted equivalents of variables with
+tainted values
+.cindex "tainted data" "de-tainting"
+come down to using the tainted value as a lookup key in a trusted database.
+This database could be the filesystem structure,
+or the password file,
+or accessed via a DBMS.
+Specific methods are indexed under &"de-tainting"&.
+.wen
+
.section "Literal text in expanded strings" "SECTlittext"
those headers that contain lists of addresses, a comma is also inserted at the
junctions between headers. This does not happen for the &%rheader%& expansion.
-.new
.cindex "tainted data"
When the headers are from an incoming message,
the result of expanding any of these variables is tainted.
-.wen
.vitem &*${hmac{*&<&'hashname'&>&*}{*&<&'secret'&>&*}{*&<&'string'&>&*}}*&
You can use &`fail`& instead of {<&'string3'&>} as in a string extract.
-.vitem "&*${lookup{*&<&'key'&>&*}&~*&<&'search&~type'&>&*&~&&&
- {*&<&'file'&>&*}&~{*&<&'string1'&>&*}&~{*&<&'string2'&>&*}}*&"
-This is the first of one of two different types of lookup item, which are both
-described in the next item.
+.new
+.vitem &*${listquote{*&<&'separator'&>&*}{*&<&'string'&>&*}}*&
+.cindex quoting "for list"
+.cindex list quoting
+This item doubles any occurrence of the separator character
+in the given string.
+An empty string is replaced with a single space.
+This converts the string into a safe form for use as a list element,
+in a list using the given separator.
+.wen
+
-.vitem "&*${lookup&~*&<&'search&~type'&>&*&~{*&<&'query'&>&*}&~&&&
+.vitem "&*${lookup&~{*&<&'key'&>&*}&~*&<&'search&~type'&>&*&~&&&
+ {*&<&'file'&>&*}&~{*&<&'string1'&>&*}&~{*&<&'string2'&>&*}}*&" &&&
+ "&*${lookup&~*&<&'search&~type'&>&*&~{*&<&'query'&>&*}&~&&&
{*&<&'string1'&>&*}&~{*&<&'string2'&>&*}}*&"
.cindex "expansion" "lookup in"
.cindex "file" "lookups"
${readsocket{/socket/name}{request string}{3s:shutdown=no}}
.endd
-.new
The following option names are recognised:
.ilist
&*cache*&
Values are &"yes"& or &"no"& (the default).
If it is enabled, a shutdown as descripbed above is never done.
.endlist
-.wen
A fourth argument allows you to change any newlines that are in the data
As a more realistic example, in an ACL you might have
.code
-deny message = Too many bad recipients
- condition = \
+deny condition = \
${if and { \
{>{$rcpt_count}{10}} \
{ \
{${eval:$rcpt_count/2}} \
} \
}{yes}{no}}
+ message = Too many bad recipients
.endd
The condition is true if there have been more than 10 RCPT commands and
fewer than half of them have resulted in a valid recipient.
is done by calling the &[stat()]& function. The use of the &%exists%& test in
users' filter files may be locked out by the system administrator.
+.new
+&*Note:*& Testing a path using this condition is not a sufficient way of
+de-tainting it.
+.wen
+
.vitem &*first_delivery*&
.cindex "delivery" "first"
.cindex "first delivery"
There can be problems if any of the strings are permitted to contain colon
characters. In the usual way, these have to be doubled to avoid being taken as
-separators. If the data is being inserted from a variable, the &%sg%& expansion
-item can be used to double any existing colons. For example, the configuration
+separators.
+The &%listquote%& expansion item can be used for this.
+For example, the configuration
of a LOGIN authenticator might contain this setting:
.code
-server_condition = ${if pam{$auth1:${sg{$auth2}{:}{::}}}}
-.endd
-For a PLAIN authenticator you could use:
-.code
-server_condition = ${if pam{$auth2:${sg{$auth3}{:}{::}}}}
+server_condition = ${if pam{$auth1:${listquote{:}{$auth2}}}}
.endd
In some operating systems, PAM authentication can be done only from a process
running as root. Since Exim is running as the Exim user when receiving
.vindex "&$config_file$&"
The name of the main configuration file Exim is using.
-.vitem &$dmarc_domain_policy$& &&&
- &$dmarc_status$& &&&
- &$dmarc_status_text$& &&&
- &$dmarc_used_domains$&
-Results of DMARC verification.
-For details see section &<<SECDMARC>>&.
-
.vitem &$dkim_verify_status$&
Results of DKIM verification.
For details see section &<<SECDKIMVFY>>&.
a colon-separated list of signer domains and identities for the message.
For details see section &<<SECDKIMVFY>>&.
+.vitem &$dmarc_domain_policy$& &&&
+ &$dmarc_status$& &&&
+ &$dmarc_status_text$& &&&
+ &$dmarc_used_domains$&
+Results of DMARC verification.
+For details see section &<<SECDMARC>>&.
+
.vitem &$dnslist_domain$& &&&
&$dnslist_matched$& &&&
&$dnslist_text$& &&&
the complete argument of the ETRN command (see section &<<SECTETRN>>&).
.endlist
-.new
.cindex "tainted data"
If the origin of the data is an incoming message,
-the result of expanding this variable is tainted.
-When un untainted version is needed, one should be obtained from
+the result of expanding this variable is tainted and may not
+be further expanded or used as a filename.
+When an untainted version is needed, one should be obtained from
looking up the value in a local (therefore trusted) database.
Often &$domain_data$& is usable in this role.
-.wen
.vitem &$domain_data$&
.vindex "&$domain_data$&"
-When the &%domains%& option on a router matches a domain by
-means of a lookup, the data read by the lookup is available during the running
-of the router as &$domain_data$&. In addition, if the driver routes the
+When the &%domains%& condition on a router
+.new
+or an ACL
+matches a domain
+against a list, the match value is copied to &$domain_data$&.
+This is an enhancement over previous versions of Exim, when it only
+applied to the data read by a lookup.
+For details on match values see section &<<SECTlistresults>>& et. al.
+.wen
+
+If the router routes the
address to a transport, the value is available in that transport. If the
transport is handling multiple addresses, the value from the first address is
used.
-&$domain_data$& is also set when the &%domains%& condition in an ACL matches a
-domain by means of a lookup. The data read by the lookup is available during
-the rest of the ACL statement. In all other situations, this variable expands
-to nothing.
+&$domain_data$& set in an ACL is available during
+the rest of the ACL statement.
.vitem &$exim_gid$&
.vindex "&$exim_gid$&"
allows you, for example, to do things like this:
.code
deny hosts = net-lsearch;/some/file
-message = $host_data
+ message = $host_data
.endd
.vitem &$host_lookup_deferred$&
.cindex "host name" "lookup, failure of"
because a message may have many recipients and the system filter is called just
once.
-.new
.cindex "tainted data"
If the origin of the data is an incoming message,
-the result of expanding this variable is tainted.
+the result of expanding this variable is tainted and
+may not be further expanded or used as a filename.
&*Warning*&: the content of this variable is usually provided by a potential
attacker.
Often &$local_part_data$& is usable in this role.
If needed, use a router &%address_data%& or &%set%& option for
the retrieved data.
-.wen
When a message is being delivered to a file, pipe, or autoreply transport as a
result of aliasing or forwarding, &$local_part$& is set to the local part of
.vitem &$local_part_data$&
.vindex "&$local_part_data$&"
-When the &%local_parts%& option on a router matches a local part by means of a
-lookup, the data read by the lookup is available during the running of the
-router as &$local_part_data$&. In addition, if the driver routes the address
-to a transport, the value is available in that transport. If the transport is
-handling multiple addresses, the value from the first address is used.
-
+When the &%local_parts%& condition on a router or ACL
+matches a local part list
.new
-The &%check_local_user%& router option also sets this variable.
+the match value is copied to &$local_part_data$&.
+This is an enhancement over previous versions of Exim, when it only
+applied to the data read by a lookup.
+For details on match values see section &<<SECTlistresults>>& et. al.
.wen
-&$local_part_data$& is also set when the &%local_parts%& condition in an ACL
-matches a local part by means of a lookup. The data read by the lookup is
-available during the rest of the ACL statement. In all other situations, this
-variable expands to nothing.
+The &%check_local_user%& router option also sets this variable.
.vindex &$local_part_prefix$& &&&
&$local_part_prefix_v$& &&&
value of &$local_part$& during routing and subsequent delivery. The values of
any prefix or suffix are in &$local_part_prefix$& and
&$local_part_suffix$&, respectively.
-.new
.cindex "tainted data"
If the specification did not include a wildcard then
the affix variable value is not tainted.
the affix matched by the wildcard is in
&$local_part_prefix_v$& or &$local_part_suffix_v$& as appropriate,
and both the whole and varying values are tainted.
-.wen
.vitem &$local_scan_data$&
.vindex "&$local_scan_data$&"
Here is an example of the use of this variable in a DATA ACL:
.code
-deny message = Too many lines in message header
- condition = \
+deny condition = \
${if <{250}{${eval:$message_linecount - $body_linecount}}}
+ message = Too many lines in message header
.endd
In the MAIL and RCPT ACLs, the value is zero because at that stage the
message has not yet been received.
.cindex "spool" "number of messages"
This variable contains the number of messages queued.
It is evaluated on demand, but no more often than once every minute.
+If there is no daemon notifier socket open, the value will be
+an empty string.
.vitem &$r_...$&
.vindex &$r_...$&
dns_dnssec_ok = 1
.endd
-.new
In addition, on Linux with glibc 2.31 or newer the resolver library will
default to stripping out a successful validation status.
This will break a previously working Exim installation.
.code
options trust-ad
.endd
-.wen
Exim does not perform DNSSEC validation itself, instead leaving that to a
validating resolver (e.g. unbound, or bind with suitable configuration).
.vindex "&$tls_in_sni$&"
.vindex "&$tls_sni$&"
.cindex "TLS" "Server Name Indication"
+.cindex "TLS" SNI
+.cindex SNI "observability on server"
When a TLS session is being established, if the client sends the Server
Name Indication extension, the value will be placed in this variable.
If the variable appears in &%tls_certificate%& then this option and
.vitem &$tls_out_sni$&
.vindex "&$tls_out_sni$&"
.cindex "TLS" "Server Name Indication"
+.cindex "TLS" SNI
+.cindex SNI "observability in client"
During outbound
SMTP deliveries, this variable reflects the value of the &%tls_sni%& option on
the transport.
.row &%local_scan_timeout%& "timeout for &[local_scan()]&"
.row &%message_size_limit%& "for all messages"
.row &%percent_hack_domains%& "recognize %-hack for these domains"
+.row &%proxy_protocol_timeout%& "timeout for proxy protocol negotiation"
.row &%spamd_address%& "set interface to SpamAssassin"
.row &%strict_acl_vars%& "object to unset ACL variables"
+.row &%spf_smtp_comment_template%& "template for &$spf_smtp_comment$&"
.endtable
.row &%dkim_verify_keytypes%& "DKIM key types accepted for signatures"
.row &%dkim_verify_min_keysizes%& "DKIM key sizes accepted for signatures"
.row &%dkim_verify_signers%& "DKIM domains for which DKIM ACL is run"
+.row &%dmarc_forensic_sender%& "DMARC sender for report messages"
+.row &%dmarc_history_file%& "DMARC results log"
+.row &%dmarc_tld_file%& "DMARC toplevel domains file"
.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"
This option defines a template file containing paragraphs of text to be used
for constructing bounce messages. Details of the file's contents are given in
chapter &<<CHAPemsgcust>>&.
-.new
.cindex bounce_message_file "tainted data"
The option is expanded to give the file path, which must be
absolute and untainted.
-.wen
See also &%warn_message_file%&.
to handle IPv6 literal addresses.
-.new
.option dkim_verify_hashes main "string list" "sha256 : sha512"
.cindex DKIM "selecting signature algorithms"
This option gives a list of hash types which are acceptable in signatures,
-.wen
and an order of processing.
Signatures with algorithms not in the list will be ignored.
Signatures with algorithms not in the list will be ignored.
-.new
.option dkim_verify_min_keysizes main "string list" "rsa=1024 ed25519=250"
This option gives a list of key sizes which are acceptable in signatures.
The list is keyed by the algorithm type for the key; the values are in bits.
Signatures with keys smaller than given by this option will fail verification.
The default enforces the RFC 8301 minimum key size for RSA signatures.
-.wen
.option dkim_verify_minimal main boolean false
If set to true, verification of signatures will terminate after the
See section &<<SECDKIMVFY>>&.
+.option dmarc_forensic_sender main string&!! unset
+.option dmarc_history_file main string unset
+.option dmarc_tld_file main string unset
+.cindex DMARC "main section options"
+These options control DMARC processing.
+See section &<<SECDMARC>>& for details.
+
+
.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
If the resolver library does not support DNSSEC then this option has no effect.
-.new
On Linux with glibc 2.31 or newer this is insufficient, the resolver library
will default to stripping out a successful validation status.
This will break a previously working Exim installation.
.code
options trust-ad
.endd
-.wen
.option dns_ipv4_lookup main "domain list&!!" unset
A NOTIFY=SUCCESS option requests success-DSN messages.
A NOTIFY= option with no argument requests that no delay or failure DSNs
are sent.
-.new
&*Note*&: Supplying success-DSN messages has been criticised
on privacy grounds; it can leak details of internal forwarding.
-.wen
.option dsn_from main "string&!!" "see below"
.cindex "&'From:'& header line" "in bounces"
transport driver.
-.new
.option notifier_socket main string "$spool_directory/exim_daemon_notify"
This option gives the name for a unix-domain socket on which the daemon
listens for work and information-requests.
The option is expanded before use.
If the platform supports Linux-style abstract socket names, the result
is used with a nul byte prefixed.
-Otherwise, it should be a full path name and use a directory accessible
+Otherwise,
+.new "if nonempty,"
+it should be a full path name and use a directory accessible
to Exim.
-If the Exim command line uses a &%-oX%& option and does not use &%-oP%&
-then a notifier socket is not created.
+.new
+If this option is set as empty,
+or the command line &%-oY%& option is used, or
.wen
+the command line uses a &%-oX%& option and does not use &%-oP%&,
+then a notifier socket is not created.
.option openssl_options main "string list" "+no_sslv2 +no_sslv3 +single_dh_use +no_ticket +no_renegotiation"
&%queue_list_requires_admin%& and &%commandline_checks_require_admin%&.
+.new
+.option proxy_protocol_timeout main time 3s
+.cindex proxy "proxy protocol"
+This option sets the timeout for proxy protocol negotiation.
+For details see section &<<SECTproxyInbound>>&.
+.wen
+
+
.option qualify_domain main string "see below"
.cindex "domain" "for qualifying addresses"
.cindex "address" "qualification"
deliveries if the configuration allows a delivery attempt as soon as a message
is received.
+See also the &%max_parallel%& generic transport option,
+and the &%serialize_hosts%& smtp transport option.
+
.cindex "number of deliveries"
.cindex "delivery" "maximum number of"
If you want to control the total number of deliveries on the system, you
smtp_etrn_command = /etc/etrn_command $domain \
$sender_host_address
.endd
-.new
If the option is not set, the argument for the ETRN command must
be a &'#'& followed by an address string.
In this case an &'exim -R <string>'& command is used;
if the ETRN ACL has set up a named-queue then &'-MCG <queue>'& is appended.
-.wen
A new process is created to run the command, but Exim does not wait for it to
complete. Consequently, its status cannot be checked. If the command cannot be
This option is available when Exim is compiled with SPF support.
See section &<<SECSPF>>& for more details.
+.option spf_smtp_comment_template main string&!! "Please%_see%_http://www.open-spf.org/Why"
+This option is available when Exim is compiled with SPF support. It
+allows the customisation of the SMTP comment that the SPF library
+generates. You are strongly encouraged to link to your own explanative
+site. The template must not contain spaces. If you need spaces in the
+output, use the proper placeholder. If libspf2 can not parse the
+template, it uses a built-in default broken link. The following placeholders
+(along with Exim variables (but see below)) are allowed in the template:
+.ilist
+&*%_*&: A space.
+.next
+&*%{L}*&: Envelope sender's local part.
+.next
+&*%{S}*&: Envelope sender.
+.next
+&*%{O}*&: Envelope sender's domain.
+.next
+&*%{D}*&: Current(?) domain.
+.next
+&*%{I}*&: SMTP client Ip.
+.next
+&*%{C}*&: SMTP client pretty IP.
+.next
+&*%{T}*&: Epoch time (UTC).
+.next
+&*%{P}*&: SMTP client domain name.
+.next
+&*%{V}*&: IP version.
+.next
+&*%{H}*&: EHLO/HELO domain.
+.next
+&*%{R}*&: Receiving domain.
+.endlist
+The capitalized placeholders do proper URL encoding, if you use them
+lowercased, no encoding takes place. This list was compiled from the
+libspf2 sources.
+
+A note on using Exim variables: As
+currently the SPF library is initialized before the SMTP EHLO phase,
+the variables useful for expansion are quite limited.
.option split_spool_directory main boolean false
.option syslog_timestamp main boolean true
.cindex "syslog" "timestamps"
+.cindex timestamps syslog
If &%syslog_timestamp%& is set false, the timestamps on Exim's log lines are
omitted when these lines are sent to syslog. See chapter &<<CHAPlog>>& for
details of Exim's logging.
file is used, the &$tls_in_ourcert$& variable is unreliable.
The macro "_TLS_BAD_MULTICERT_IN_OURCERT" will be defined for those versions.
+.cindex SNI "selecting server certificate based on"
If the option contains &$tls_out_sni$& and Exim is built against OpenSSL, then
if the OpenSSL build supports TLS extensions and the TLS client sends the
Server Name Indication extension, then this option and others documented in
the value is a file then the certificates are sent by Exim as a server to
connecting clients, defining the list of accepted certificate authorities.
Thus the values defined should be considered public data. To avoid this,
-use the explicit directory version.
+use the explicit directory version. (If your peer is Exim up to 4.85,
+using GnuTLS, you may need to send the CAs (thus using the file
+variant). Otherwise the peer doesn't send its certificate.)
See &<<SECTtlssni>>& for discussion of when this option might be re-expanded.
been in the queue for a specified amount of time, as specified by
&%delay_warning%&. Details of the file's contents are given in chapter
&<<CHAPemsgcust>>&.
-.new
.cindex warn_message_file "tainted data"
The option is expanded to give the file path, which must be
absolute and untainted.
-.wen
See also &%bounce_message_file%&.
local system. The check is done by calling the &[getpwnam()]& function rather
than trying to read &_/etc/passwd_& directly. This means that other methods of
holding password data (such as NIS) are supported. If the local part is a local
-user, &$home$& is set from the password data, and can be tested in other
+user,
+.cindex "tainted data" "de-tainting"
+&$local_part_data$& is set to an untainted version of the local part and
+&$home$& is set from the password data. The latter can be tested in other
preconditions that are evaluated after this one (the order of evaluation is
given in section &<<SECTrouprecon>>&). However, the value of &$home$& can be
overridden by &%router_home_directory%&. If the local part is not a local user,
that is associated with any addresses that are accepted by the router.
However, the option has no effect when an address is just being verified.
Each list item is separately expanded, at transport time.
-.new
If an item ends in *, it will match any header with the given prefix.
-.wen
The way in which
the text is used to remove header lines at transport time is described in
section &<<SECTheadersaddrem>>&. Header lines are not actually removed until
This behaviour can be overridden by setting &%rcpt_include_affixes%& true on
the relevant transport.
-.new
.vindex &$local_part_prefix_v$&
If wildcarding (above) was used then the part of the prefix matching the
wildcard is available in &$local_part_prefix_v$&.
-.wen
When an address is being verified, &%local_part_prefix%& affects only the
behaviour of the router. If the callout feature of verification is in use, this
yield empty addresses, for example, items containing only RFC 2822 address
comments.
-.new
.cindex "tainted data" "in filenames"
.cindex redirect "tainted data"
Tainted data may not be used for a filename.
In the examples above, &$local_part$& is used for looking up data held locally
on the system, and not used directly (the second example derives &$home$& via
the passsword file or database, using &$local_part$&).
-.wen
.code
list1: :include:/opt/lists/list1
.endd
-.new
.cindex "tainted data" "in filenames"
.cindex redirect "tainted data"
Tainted data may not be used for a filename.
-.wen
.next
.cindex "address redirection" "to black hole"
.cindex "delivery" "discard"
If the result of the expansion is an empty string, or if the expansion
is forced to fail, no action is taken. Other expansion failures are treated as
errors and cause the delivery to be deferred.
-.new
If an item ends in *, it will match any header with the given prefix.
-.wen
Matching headers are omitted from the message as it is transported, as described
in section &<<SECTheadersaddrem>>&. Header removal can also be specified by
used to determine the file or directory name for the delivery. Normally, the
contents of &$address_file$& are used in some way in the string expansion.
.endlist
-.new
.cindex "tainted data" "in filenames"
.cindex appendfile "tainted data"
Tainted data may not be used for a file or directory name.
This means that, for instance, &$local_part$& cannot be used directly
as a component of a path. It can however be used as the key for a lookup
which returns a path (or component).
-.wen
.cindex "Sieve filter" "configuring &(appendfile)&"
details of the local delivery environment and chapter &<<CHAPbatching>>&
for a discussion of local delivery batching.
-.new
.cindex "tainted data" "in pipe command"
.cindex pipe "tainted data"
Tainted data may not be used for the command name.
-.wen
.section "Concurrent delivery" "SECID140"
.option command_timeout smtp time 5m
+.cindex timeout "smtp transport command"
This sets a timeout for receiving a response to an SMTP command that has been
sent out. It is also used when waiting for the initial banner line from the
remote host. Its value must not be zero.
.option connect_timeout smtp time 5m
+.cindex timeout "smtp transport connect"
This sets a timeout for the &[connect()]& function, which sets up a TCP/IP call
to a remote host. A setting of zero allows the system timeout (typically
several minutes) to act. To have any effect, the value of this option must be
.option data_timeout smtp time 5m
+.cindex timeout "for transmitted SMTP data blocks"
This sets a timeout for the transmission of each block in the data portion of
the message. As a result, the overall timeout for a message depends on the size
of the message. Its value must not be zero. See also &%final_timeout%&.
.option final_timeout smtp time 10m
+.cindex timeout "for transmitted SMTP data accept"
This is the timeout that applies while waiting for the response to the final
line containing just &"."& that terminates a message. Its value must not be
zero.
.cindex "RFC 3030" "CHUNKING"
This option provides a list of servers to which, provided they announce
CHUNKING support, Exim will attempt to use BDAT commands rather than DATA.
-.new
Unless DKIM signing is being done,
-.wen
BDAT will not be used in conjunction with a transport filter.
.option hosts_try_dane smtp "host list&!!" *
permits this.
+.new
+.option message_linelength_limit smtp integer 998
+.cindex "line length" limit
+This option sets the maximum line length, in bytes, that the transport
+will send. Any messages with lines exceeding the given value
+will fail and a failure-DSN ("bounce") message will if possible be returned
+to the sender.
+The default value is that defined by the SMTP standards.
+
+It is generally wise to also check in the data ACL so that messages
+received via SMTP can be refused without producing a bounce.
+.wen
+
+
.option multi_domain smtp boolean&!! true
.vindex "&$domain$&"
When this option is set, the &(smtp)& transport can handle a number of
&$address_data$&, &$domain_data$&, &$local_part_data$&,
&$host$&, &$host_address$& and &$host_port$&.
+.new
+If the connection is DANE-enabled then this option is ignored;
+only messages having the domain used for the DANE TLSA lookup are
+sent on the connection.
+.wen
+
.option port smtp string&!! "see below"
.cindex "port" "sending TCP/IP"
.cindex "TCP/IP" "setting outgoing port"
.option tls_sni smtp string&!! unset
.cindex "TLS" "Server Name Indication"
+.cindex "TLS" SNI
+.cindex SNI "setting in client"
.vindex "&$tls_sni$&"
-If this option is set then it sets the $tls_out_sni variable and causes any
+If this option is set
+.new
+and the connection is not DANE-validated
+.wen
+then it sets the $tls_out_sni variable and causes any
TLS session to pass this value as the Server Name Indication extension to
the remote side, which can be used by the remote side to select an appropriate
certificate and private key for the session.
option is passed. When authentication succeeds, the identity of the user
who authenticated is placed in &$auth1$&.
-.new
The Dovecot configuration to match the above wil look
something like:
.code
auth_mechanisms = plain login ntlm
.endd
-.wen
.ecindex IIDdcotauth1
.ecindex IIDdcotauth2
made that any particular new authentication mechanism will be supported
without code changes in Exim.
-.new
The library is expected to add support in an upcoming
realease for the SCRAM-SHA-256 method.
The macro _HAVE_AUTH_GSASL_SCRAM_SHA_256 will be defined
.option client_username gsasl string&!! unset
This option is exapanded before use, and should result in
the account name to be used.
-.wen
-.new
.option client_spassword gsasl string&!! unset
If a SCRAM mechanism is being used and this option is set
it is used in preference to &%client_password%&.
with the PBKDF2-prepared password, hex-encoded.
Note that this value will depend on the salt and iteration-count
supplied by the server.
-.wen
non-issue, as a man-in-the-middle attack will cause the correct client and
server to see different identifiers and authentication will fail.
-.new
This is
only usable by mechanisms which support "channel binding"; at time of
writing, that's the SCRAM family.
When using this feature the "-PLUS" variants of the method names need to be used.
-.wen
This defaults off to ensure smooth upgrade across Exim releases, in case
this option causes some clients to start failing. Some future release
.option server_scram_iter gsasl string&!! 4096
This option provides data for the SCRAM family of mechanisms.
-.new
The &$auth1$&, &$auth2$& and &$auth3$& variables are available
when this option is expanded.
either the iteration count or the salt).
A minimum value of 4096 is required by the standards
for all current SCRAM mechanism variants.
-.wen
.option server_scram_salt gsasl string&!! unset
This option provides data for the SCRAM family of mechanisms.
-.new
The &$auth1$&, &$auth2$& and &$auth3$& variables are available
when this option is expanded.
The value should be a base64-encoded string,
of random data typically 4-to-16 bytes long.
If unset or empty after expansion the library will provides a value for the
protocol conversation.
-.wen
-.new
.option server_key gsasl string&!! unset
.option server_skey gsasl string&!! unset
These options can be used for the SCRAM family of mechanisms
The libgsasl library release includes a utility &'gsasl'& which can be used
to generate these values.
-.wen
.option server_service gsasl string &`smtp`&
This should be documented with the feature. If the documentation does not
explicitly state that the feature is infeasible in the other TLS
implementation, then patches are welcome.
+.new
+.next
+The output from "exim -bV" will show which (if any) support was included
+in the build.
+Also, the macro "_HAVE_OPENSSL" or "_HAVE_GNUTLS" will be defined.
+.wen
.endlist
.endd
+.new
+.section "Caching of static server configuration items" "SECTserverTLScache"
+.cindex certificate caching
+.cindex privatekey caching
+.cindex crl caching
+.cindex ocsp caching
+.cindex ciphers caching
+.cindex "CA bundle" caching
+.cindex "certificate authorities" caching
+.cindex tls_certificate caching
+.cindex tls_privatekey caching
+.cindex tls_crl caching
+.cindex tls_ocsp_file caching
+.cindex tls_require_ciphers caching
+.cindex tls_verify_certificate caching
+.cindex caching certificate
+.cindex caching privatekey
+.cindex caching crl
+.cindex caching ocsp
+.cindex caching ciphers
+.cindex caching "certificate authorities
+If any of the main configuration options &%tls_certificate%&, &%tls_privatekey%&,
+&%tls_crl%& and &%tls_ocsp_file%& have values with no
+expandable elements,
+then the associated information is loaded at daemon startup.
+It is made available
+to child processes forked for handling received SMTP connections.
+
+This caching is currently only supported under Linux and FreeBSD.
+
+If caching is not possible, for example if an item has to be dependent
+on the peer host so contains a &$sender_host_name$& expansion, the load
+of the associated information is done at the startup of the TLS connection.
+
+The cache is invalidated and reloaded after any changes to the directories
+containing files specified by these options.
+
+The information specified by the main option &%tls_verify_certificates%&
+is similarly cached so long as it specifies files explicitly
+or (under GnuTLS) is the string &"system,cache"&.
+The latter case is not automatically invalidated;
+it is the operator's responsibility to arrange for a daemon restart
+any time the system certificate authority bundle is updated.
+A HUP signal is sufficient for this.
+The value &"system"& results in no caching under GnuTLS.
+
+The macro _HAVE_TLS_CA_CACHE will be defined if the suffix for "system"
+is acceptable in configurations for the Exim executavble.
+
+Caching of the system Certificate Authorities bundle can
+save siginificant time and processing on every TLS connection
+accepted by Exim.
+.wen
+
+
.section "Configuring an Exim client to use TLS" "SECTclientTLS"
The &%tls_certificate%& and &%tls_privatekey%& options of the &(smtp)&
transport provide the client with a certificate, which is passed to the server
-if it requests it. If the server is Exim, it will request a certificate only if
+if it requests it.
+This is an optional thing for TLS connections, although either end
+may insist on it.
+If the server is Exim, it will request a certificate only if
&%tls_verify_hosts%& or &%tls_try_verify_hosts%& matches the client.
&*Note*&: Do not use a certificate which has the OCSP-must-staple extension,
or need not succeed respectively.
The &%tls_verify_cert_hostnames%& option lists hosts for which additional
-checks are made: that the host name (the one in the DNS A record)
-is valid for the certificate.
+name checks are made on the server certificate.
+.new
+The match against this list is, as per other Exim usage, the
+IP for the host. That is most closely associated with the
+name on the DNS A (or AAAA) record for the host.
+However, the name that needs to be in the certificate
+is the one at the head of any CNAME chain leading to the A record.
+.wen
The option defaults to always checking.
The &(smtp)& transport has two OCSP-related options:
+.new
+.section "Caching of static client configuration items" "SECTclientTLScache"
+.cindex certificate caching
+.cindex privatekey caching
+.cindex crl caching
+.cindex ciphers caching
+.cindex "CA bundle" caching
+.cindex "certificate authorities" caching
+.cindex tls_certificate caching
+.cindex tls_privatekey caching
+.cindex tls_crl caching
+.cindex tls_require_ciphers caching
+.cindex tls_verify_certificate caching
+.cindex caching certificate
+.cindex caching privatekey
+.cindex caching crl
+.cindex caching ciphers
+.cindex caching "certificate authorities
+If any of the transport configuration options &%tls_certificate%&, &%tls_privatekey%&
+and &%tls_crl%& have values with no
+expandable elements,
+then the associated information is loaded per smtp transport
+at daemon startup, at the start of a queue run, or on a
+command-line specified message delivery.
+It is made available
+to child processes forked for handling making SMTP connections.
+
+This caching is currently only supported under Linux.
+
+If caching is not possible, the load
+of the associated information is done at the startup of the TLS connection.
+
+The cache is invalidated in the daemon
+and reloaded after any changes to the directories
+containing files specified by these options.
+
+The information specified by the main option &%tls_verify_certificates%&
+is similarly cached so long as it specifies files explicitly
+or (under GnuTLS) is the string &"system,cache"&.
+The latter case is not automatically invaludated;
+it is the operator's responsibility to arrange for a daemon restart
+any time the system certificate authority bundle is updated.
+A HUP signal is sufficient for this.
+The value &"system"& results in no caching under GnuTLS.
+
+The macro _HAVE_TLS_CA_CACHE will be defined if the suffix for "system"
+is acceptable in configurations for the Exim executavble.
+
+Caching of the system Certificate Authorities bundle can
+save siginificant time and processing on every TLS connection
+initiated by Exim.
+.wen
+
+
+
+
.section "Use of TLS Server Name Indication" "SECTtlssni"
.cindex "TLS" "Server Name Indication"
+.cindex "TLS" SNI
+.cindex SNI
.vindex "&$tls_in_sni$&"
.oindex "&%tls_in_sni%&"
With TLS1.0 or above, there is an extension mechanism by which extra
only point of caution. The &$tls_out_sni$& variable will be set to this string
for the lifetime of the client connection (including during authentication).
+.new
+If DANE validated the connection attempt then the value of the &%tls_sni%& option
+is forced to the domain part of the recipient address.
+.wen
+
Except during SMTP client sessions, if &$tls_in_sni$& is set then it is a string
received from a client.
It can be logged with the &%log_selector%& item &`+tls_sni`&.
It also allows the server to declare (implicitly) that connections to it should use TLS. An MITM could simply
fail to pass on a server's STARTTLS.
-DANE scales better than having to maintain (and side-channel communicate) copies of server certificates
+DANE scales better than having to maintain (and communicate via side-channel) copies of server certificates
for every possible target server. It also scales (slightly) better than having to maintain on an SMTP
client a copy of the standard CAs bundle. It also means not having to pay a CA for certificates.
tls_verify_certificates
tls_crl
tls_verify_cert_hostnames
+ tls_sni
.endd
If DANE is not usable, whether requested or not, and CA-anchored
&%drop%&: This verb behaves like &%deny%&, except that an SMTP connection is
forcibly closed after the 5&'xx'& error message has been sent. For example:
.code
-drop message = I don't take more than 20 RCPTs
- condition = ${if > {$rcpt_count}{20}}
+drop condition = ${if > {$rcpt_count}{20}}
+ message = I don't take more than 20 RCPTs
.endd
There is no difference between &%deny%& and &%drop%& for the connect-time ACL.
The connection is always dropped after sending a 550 response.
controlled by &%acl_smtp_connect%& or &%acl_smtp_helo%&. See also
&%pipelining_advertise_hosts%&.
-.new
.vitem &*control&~=&~queue/*&<&'options'&>* &&&
&*control&~=&~queue_only*&
.oindex "&%queue%&"
The control only applies to the current message, not to any subsequent ones that
may be received in the same SMTP connection.
-.wen
.vitem &*control&~=&~submission/*&<&'options'&>
.cindex "message" "submission"
allows you, for example, to set up a statement like this:
.code
deny hosts = net-lsearch;/some/file
-message = $host_data
+ message = $host_data
.endd
which gives a custom error message for each denied host.
.cindex "header lines" "verifying header names only ASCII"
.cindex "verifying" "header names only ASCII"
This condition is relevant only in an ACL that is run after a message has been
-received, that is, in an ACL specified by &%acl_smtp_data%& or
-&%acl_not_smtp%&. It checks all header names (not the content) to make sure
+received.
+This usually means an ACL specified by &%acl_smtp_data%& or &%acl_not_smtp%&.
+It checks all header names (not the content) to make sure
there are no non-ASCII characters, also excluding control characters. The
allowable characters are decimal ASCII values 33 through 126.
condition to restrict it to bounce messages only:
.code
deny senders = :
- message = A valid sender header is required for bounces
!verify = header_sender
+ message = A valid sender header is required for bounces
.endd
.vitem &*verify&~=&~header_syntax*&
(eg. is generated from the received message)
they must be protected from the options parsing by doubling:
.code
-verify = sender=${sg{${address:$h_sender:}}{/}{//}}
+verify = sender=${listquote{/}{${address:$h_sender:}}}
.endd
.endlist
warn for one list and block for another, you can use two different statements:
.code
deny dnslists = blackholes.mail-abuse.org
-warn message = X-Warn: sending host is on dialups list
- dnslists = dialups.mail-abuse.org
+warn dnslists = dialups.mail-abuse.org
+ message = X-Warn: sending host is on dialups list
.endd
.cindex caching "of dns lookup"
.cindex DNS TTL
with these lists. You can change the name that is looked up in a DNS list by
listing it after the domain name, introduced by a slash. For example,
.code
-deny message = Sender's domain is listed at $dnslist_domain
- dnslists = dsn.rfc-ignorant.org/$sender_address_domain
+deny dnslists = dsn.rfc-ignorant.org/$sender_address_domain
+ message = Sender's domain is listed at $dnslist_domain
.endd
This particular example is useful only in ACLs that are obeyed after the
RCPT or DATA commands, when a sender address is available. If (for
However, when the data for the list is obtained from a lookup, the second form
is usually much more convenient. Consider this example:
.code
-deny message = The mail servers for the domain \
+deny dnslists = sbl.spamhaus.org/<|${lookup dnsdb {>|a=<|\
+ ${lookup dnsdb {>|mxh=\
+ $sender_address_domain} }} }
+ message = The mail servers for the domain \
$sender_address_domain \
are listed at $dnslist_domain ($dnslist_value); \
see $dnslist_text.
- dnslists = sbl.spamhaus.org/<|${lookup dnsdb {>|a=<|\
- ${lookup dnsdb {>|mxh=\
- $sender_address_domain} }} }
.endd
Note the use of &`>|`& in the dnsdb lookup to specify the separator for
multiple DNS records. The inner dnsdb lookup produces a list of MX hosts
information.
You can use the DNS list variables in &%message%& or &%log_message%& modifiers
-&-- although these appear before the condition in the ACL, they are not
+&-- even if these appear before the condition in the ACL, they are not
expanded until after it has failed. For example:
.code
deny hosts = !+local_networks
a check that the IP being tested is indeed on the first list. The first
domain is the one that is put in &$dnslist_domain$&. For example:
.code
-deny message = \
- rejected because $sender_host_address is blacklisted \
- at $dnslist_domain\n$dnslist_text
- dnslists = \
+deny dnslists = \
sbl.spamhaus.org,sbl-xbl.spamhaus.org=127.0.0.2 : \
dul.dnsbl.sorbs.net,dnsbl.sorbs.net=127.0.0.10
+ message = \
+ rejected because $sender_host_address is blacklisted \
+ at $dnslist_domain\n$dnslist_text
.endd
For the first blacklist item, this starts by doing a lookup in
&'sbl-xbl.spamhaus.org'& and testing for a 127.0.0.2 return. If there is a
The &%per_rcpt%& option causes Exim to limit the rate at which recipients are
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_mime%&, or &%acl_smtp_data%& 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 (accepted) recipient count in one go. Note that
in either case the rate limiting engine will see a message with many
.code
acl_check_connect:
deny ratelimit = 100 / 5m / readonly
- log_message = RATE CHECK: $sender_rate/$sender_rate_period \
+ log_message = RATE CHECK: $sender_rate/$sender_rate_period \
(max $sender_rate_limit)
# ...
acl_check_mail:
warn ratelimit = 100 / 5m / strict
- log_message = RATE UPDATE: $sender_rate/$sender_rate_period \
+ log_message = RATE UPDATE: $sender_rate/$sender_rate_period \
(max $sender_rate_limit)
.endd
ratelimit = 100 / 1d / strict / $authenticated_id
# System-wide rate limit
-defer message = Sorry, too busy. Try again later.
- ratelimit = 10 / 1s / $primary_hostname
+defer ratelimit = 10 / 1s / $primary_hostname
+ message = Sorry, too busy. Try again later.
# Restrict incoming rate from each host, with a default
# set using a macro and special cases looked up in a table.
-defer message = Sender rate exceeds $sender_rate_limit \
- messages per $sender_rate_period
- ratelimit = ${lookup {$sender_host_address} \
+defer ratelimit = ${lookup {$sender_host_address} \
cdb {DB/ratelimits.cdb} \
{$value} {RATELIMIT} }
+ message = Sender rate exceeds $sender_rate_limit \
+ messages per $sender_rate_period
.endd
&*Warning*&: If you have a busy server with a lot of &%ratelimit%& tests,
especially with the &%per_rcpt%& option, you may suffer from a performance
immediately after a successful redirection. By default, if a redirection
generates just one address, that address is also verified. See further
discussion in section &<<SECTredirwhilveri>>&.
+.new
+.next
+If the &%quota%& option is specified for recipient verify,
+successful routing to an appendfile transport is followed by a call into
+the transport to evaluate the quota status for the recipient.
+No actual delivery is done, but verification will succeed if the quota
+is sufficient for the message (if the sender gave a message size) or
+not already exceeded (otherwise).
+.wen
.endlist
.cindex "verifying address" "differentiating failures"
&%recipient%&: The RCPT command in a callout was rejected.
.next
&%postmaster%&: The postmaster check in a callout was rejected.
+.new
+.next
+&%quota%&: The quota check for a local recipient did non pass.
.endlist
The main use of these variables is expected to be to distinguish between
+.new
+.section "Quota caching" "SECTquotacache"
+.cindex "hints database" "quota cache"
+.cindex "quota" "cache, description of"
+.cindex "caching" "quota"
+Exim caches the results of quota verification
+in order to reduce the amount of resources used.
+The &"callout"& hints database is used.
+
+The default cache periods are five minutes for a positive (good) result
+and one hour for a negative result.
+To change the periods the &%quota%& option can be followed by an equals sign
+and a number of optional paramemters, separated by commas.
+For example:
+.code
+verify = recipient/quota=cachepos=1h,cacheneg=1d
+.endd
+Possible parameters are:
+.vlist
+.vitem &*cachepos&~=&~*&<&'time&~interval'&>
+.cindex "quota cache" "positive entry expiry, specifying"
+Set the lifetime for a positive cache entry.
+A value of zero seconds is legitimate.
+
+.vitem &*cacheneg&~=&~*&<&'time&~interval'&>
+.cindex "quota cache" "negative entry expiry, specifying"
+As above, for a negative entry.
+
+.vitem &*no_cache*&
+Set both positive and negative lifetimes to zero.
+.wen
+
.section "Sender address verification reporting" "SECTsenaddver"
.cindex "verifying" "suppressing error details"
See section &<<SECTaddressverification>>& for a general discussion of
use this:
.code
# Bounces: drop unsigned addresses for BATV senders
-deny message = This address does not send an unsigned reverse path
- senders = :
+deny senders = :
recipients = +batv_senders
+ message = This address does not send an unsigned reverse path
# Bounces: In case of prvs-signed address, check signature.
-deny message = Invalid reverse path signature.
- senders = :
+deny senders = :
condition = ${prvscheck {$local_part@$domain}\
{PRVSCHECK_SQL}{1}}
!condition = $prvscheck_result
+ message = Invalid reverse path signature.
.endd
The first statement rejects recipients for bounce messages that are addressed
to plain BATV sender addresses, because it is known that BATV senders do not
Here is a very simple scanning example:
.code
-deny message = This message contains malware ($malware_name)
- malware = *
+deny malware = *
+ message = This message contains malware ($malware_name)
.endd
The next example accepts messages when there is a problem with the scanner:
.code
-deny message = This message contains malware ($malware_name)
- malware = */defer_ok
+deny malware = */defer_ok
+ message = This message contains malware ($malware_name)
.endd
The next example shows how to use an ACL variable to scan with both sophie and
aveserver. It assumes you have set:
.endd
in the main Exim configuration.
.code
-deny message = This message contains malware ($malware_name)
- set acl_m0 = sophie
+deny set acl_m0 = sophie
malware = *
+ message = This message contains malware ($malware_name)
-deny message = This message contains malware ($malware_name)
- set acl_m0 = aveserver
+deny set acl_m0 = aveserver
malware = *
+ message = This message contains malware ($malware_name)
.endd
.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
-deny message = This message was classified as SPAM
- spam = joe
+deny spam = joe
+ message = This message was classified as SPAM
.endd
The right-hand side of the &%spam%& condition specifies a name. This is
relevant if you have set up multiple SpamAssassin profiles. If you do not want
are quite small, it is recommended that you do not scan the big ones. For
example:
.code
-deny message = This message was classified as SPAM
- condition = ${if < {$message_size}{10K}}
+deny condition = ${if < {$message_size}{10K}}
spam = nobody
+ message = This message was classified as SPAM
.endd
The &%spam%& condition returns true if the threshold specified in the user's
statement block), append &`/defer_ok`& to the right-hand side of the
spam condition, like this:
.code
-deny message = This message was classified as SPAM
- spam = joe/defer_ok
+deny spam = joe/defer_ok
+ message = This message was classified as SPAM
.endd
This causes messages to be accepted even if there is a problem with &%spamd%&.
add_header = Subject: *SPAM* $h_Subject:
# reject spam at high scores (> 12)
-deny message = This message scored $spam_score spam points.
- spam = nobody:true
+deny spam = nobody:true
condition = ${if >{$spam_score_int}{120}{1}{0}}
+ message = This message scored $spam_score spam points.
.endd
alternative plain text), while allowing HTML files to be attached. HTML
coverletter mail attached to non-HTML coverletter mail will also be allowed:
.code
-deny message = HTML mail is not accepted here
-!condition = $mime_is_rfc822
-condition = $mime_is_coverletter
-condition = ${if eq{$mime_content_type}{text/html}{1}{0}}
+deny !condition = $mime_is_rfc822
+ condition = $mime_is_coverletter
+ condition = ${if eq{$mime_content_type}{text/html}{1}{0}}
+ message = HTML mail is not accepted here
.endd
.vitem &$mime_is_multipart$&
with more backslashes, or use the &`\N`& facility to disable expansion.
Here is a simple example that contains two regular expressions:
.code
-deny message = contains blacklisted regex ($regex_match_string)
- regex = [Mm]ortgage : URGENT BUSINESS PROPOSAL
+deny regex = [Mm]ortgage : URGENT BUSINESS PROPOSAL
+ message = contains blacklisted regex ($regex_match_string)
.endd
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
LOCAL_SCAN_SOURCE=Local/local_scan.c
.endd
for example. The function must be called &[local_scan()]&;
-.new
the source file(s) for it should first #define LOCAL_SCAN
and then #include "local_scan.h".
-.wen
It is called by
Exim after it has received a message, when the success return code is about to
be sent. This is after all the ACLs have been run. The return code from your
arguments. It flushes the output stream, and returns a non-zero value if there
is an error.
-.new
.vitem &*void&~*store_get(int,BOOL)*&
This function accesses Exim's internal store (memory) manager. It gets a new
chunk of memory whose size is given by the first argument.
FALSE if it is locally-sourced.
Exim bombs out if it ever
runs out of memory. See the next section for a discussion of memory handling.
-.wen
.vitem &*void&~*store_get_perm(int,BOOL)*&
This function is like &'store_get()'&, but it always gets memory from the
.section "Per-address filtering" "SECTperaddfil"
-.vindex "&$domain$&"
-.vindex "&$local_part$&"
+.vindex "&$domain_data$&"
+.vindex "&$local_part_data$&"
In contrast to the system filter, which is run just once per message for each
delivery attempt, it is also possible to set up a system-wide filtering
operation that runs once for each recipient address. In this case, variables
-such as &$local_part$& and &$domain$& can be used, and indeed, the choice of
-filter file could be made dependent on them. This is an example of a router
-which implements such a filter:
+such as &$local_part_data$& and &$domain_data$& can be used,
+and indeed, the choice of filter file could be made dependent on them.
+This is an example of a router which implements such a filter:
.code
central_filter:
check_local_user
data = ${lookup{$local_part}lsearch{/etc/mail/virtual/$domain_data}}
no_more
.endd
-.new
The &%domains%& option specifies that the router is to be skipped, unless there
is a file in the &_/etc/mail/virtual_& directory whose name is the same as the
domain that is being processed.
The &(dsearch)& lookup used results in an untainted version of &$domain$&
being placed into the &$domain_data$& variable.
-.wen
When the router runs, it looks up the local
part in the file to find a new address (or list of addresses). The &%no_more%&
.code
my_mailboxes:
driver = appendfile
- file = /var/mail/$domain/$local_part_data
+ file = /var/mail/$domain_data/$local_part_data
user = mail
.endd
This uses a directory of mailboxes for each domain. The &%user%& setting is
cases by testing the variable &$local_part_suffix$&. For example:
.code
if $local_part_suffix contains -special then
-save /home/$local_part/Mail/special
+save /home/$local_part_data/Mail/special
endif
.endd
If the filter file does not exist, or does not deal with such addresses, they
If SMTP AUTH was used for the delivery there is an additional item A=
followed by the name of the authenticator that was used.
If an authenticated identification was set up by the authenticator's &%client_set_id%&
-option, this is logged too, separated by a colon from the authenticator name.
+option, this is logged too, as a second colon-separated list item.
+Optionally (see the &%smtp_mailauth%& &%log_selector%&) there may be a third list item.
If a shadow transport was run after a successful local delivery, the log line
for the successful delivery has an item added on the end, of the form
.next
.cindex "log" "TLS SNI"
.cindex "TLS" "logging SNI"
+.cindex SNI logging
&%tls_sni%&: When a message is received over an encrypted connection, and
the remote host provided the Server Name Indication extension, the SNI is
added to the log line, preceded by SNI=.
"check address acceptance from given IP"
.irow &<<SECTdbmbuild>>& &'exim_dbmbuild'& "build a DBM file"
.irow &<<SECTfinindret>>& &'exinext'& "extract retry information"
-.irow &<<SECThindatmai>>& &'exim_dumpdb'& "dump a hints database"
-.irow &<<SECThindatmai>>& &'exim_tidydb'& "clean up a hints database"
-.irow &<<SECThindatmai>>& &'exim_fixdb'& "patch a hints database"
+.irow &<<SECTdumpdb>>& &'exim_dumpdb'& "dump a hints database"
+.irow &<<SECTtidydb>>& &'exim_tidydb'& "clean up a hints database"
+.irow &<<SECTfixdb>>& &'exim_fixdb'& "patch a hints database"
.irow &<<SECTmailboxmaint>>& &'exim_lock'& "lock a mailbox file"
.endtable
-.section "exim_dumpdb" "SECID261"
+.section "exim_dumpdb" "SECTdumpdb"
.cindex "&'exim_dumpdb'&"
The entire contents of a database are written to the standard output by the
&'exim_dumpdb'& program, which has no options or arguments other than the
-.section "exim_tidydb" "SECID262"
+.section "exim_tidydb" "SECTtidydb"
.cindex "&'exim_tidydb'&"
The &'exim_tidydb'& utility program is used to tidy up the contents of a hints
database. If run with no options, it removes all records that are more than 30
-.section "exim_fixdb" "SECID263"
+.section "exim_fixdb" "SECTfixdb"
.cindex "&'exim_fixdb'&"
The &'exim_fixdb'& program is a utility for interactively modifying databases.
Its main use is for testing Exim, but it might also be occasionally useful for
. ////////////////////////////////////////////////////////////////////////////
. ////////////////////////////////////////////////////////////////////////////
-.chapter "DKIM, SPF and DMARC" "CHAPdkim" &&&
- "DKIM, SPF and DMARC Support"
+.chapter "DKIM, SPF, SRS and DMARC" "CHAPdkim" &&&
+ "DKIM, SPF, SRS and DMARC Support"
.section "DKIM (DomainKeys Identified Mail)" SECDKIM
.cindex "DKIM"
Signing is enabled by setting private options on the SMTP transport.
These options take (expandable) strings as arguments.
-.option dkim_domain smtp string list&!! unset
+.option dkim_domain smtp "string list&!!" unset
The domain(s) you want to sign with.
After expansion, this can be a list.
Each element in turn,
If it is empty after expansion, DKIM signing is not done,
and no error will result even if &%dkim_strict%& is set.
-.option dkim_selector smtp string list&!! unset
+.option dkim_selector smtp "string list&!!" unset
This sets the key selector string.
After expansion, which can use &$dkim_domain$&, this can be a list.
Each element in turn is put in the expansion
whether or not each header is present in the message.
The default list is available for the expansion in the macro
&"_DKIM_SIGN_HEADERS"&
-.new
and an oversigning variant is in &"_DKIM_OVERSIGN_HEADERS"&.
-.wen
If a name is repeated, multiple headers by that name (or the absence thereof)
will be signed. The textually later headers in the headers part of the
.vitem &%$dkim_key_length%&
Number of bits in the key.
-.new
Valid only once the key is loaded, which is at the time the header signature
is verified, which is after the body hash is.
-.wen
Note that RFC 8301 says:
.code
.code
# Warn when Mail purportedly from GMail has no gmail signature
-warn log_message = GMail sender without gmail.com DKIM signature
- sender_domains = gmail.com
+warn sender_domains = gmail.com
dkim_signers = gmail.com
dkim_status = none
+ log_message = GMail sender without gmail.com DKIM signature
.endd
Note that the above does not check for a total lack of DKIM signing;
to restrict an ACL verb to a list of verification outcomes, for example:
.code
-deny message = Mail from Paypal with invalid/missing signature
- sender_domains = paypal.com:paypal.de
+deny sender_domains = paypal.com:paypal.de
dkim_signers = paypal.com:paypal.de
dkim_status = none:invalid:fail
+ message = Mail from Paypal with invalid/missing signature
.endd
The possible status keywords are: 'none','invalid','fail' and 'pass'. Please
message = $sender_host_address is not allowed to send mail from \
${if def:sender_address_domain \
{$sender_address_domain}{$sender_helo_name}}. \
- Please see http://www.open-spf.org/Why?scope=\
- ${if def:sender_address_domain {mfrom}{helo}};\
+ Please see http://www.open-spf.org/Why;\
identity=${if def:sender_address_domain \
{$sender_address}{$sender_helo_name}};\
ip=$sender_host_address
.endd
+Note: The above mentioned URL may not be as helpful as expected. You are
+encouraged to replace the link with a link to a site with more
+explanations.
+
When the spf condition has run, it sets up several expansion
variables:
.vitem &$spf_smtp_comment$&
.vindex &$spf_smtp_comment$&
+.vindex &%spf_smtp_comment_template%&
This contains a string that can be used in a SMTP response
to the calling party. Useful for "fail".
+ The string is generated by the SPF library from the template configured in the main config
+ option &%spf_smtp_comment_template%&.
.endlist
.code
#macro
SRS_SECRET = <pick something unique for your site for this. Use on all MXs.>
-
+
#routers
outbound:
transport = ${if eq {$local_part@$domain} \
{$original_local_part@$original_domain} \
{remote_smtp} {remote_forwarded_smtp}}
-
+
inbound_srs:
driver = redirect
senders = :
# detect inbound bounces which are SRS'd, and decode them
condition = ${if inbound_srs {$local_part} {SRS_SECRET}}
data = $srs_recipient
-
+
inbound_srs_failure:
driver = redirect
senders = :
#... further routers here
-
+
# transport; should look like the non-forward outbound
# one, plus the max_rcpt and return_path options
remote_forwarded_smtp:
the most current version can be downloaded
from a link at &url(https://publicsuffix.org/list/public_suffix_list.dat).
See also the util/renew-opendmarc-tlds.sh script.
-.new
The default for the option is unset.
If not set, DMARC processing is disabled.
-.wen
The &%dmarc_history_file%& option, if set
&'reject '& The DMARC check failed and the library recommends rejecting the email.
&'quarantine '& The DMARC check failed and the library recommends keeping it for further inspection.
&'none '& The DMARC check passed and the library recommends no specific action, neutral.
-&'norecord '& No policy section in the DMARC record for this sender domain.
+&'norecord '& No policy section in the DMARC record for this RFC5322.From field
&'nofrom '& Unable to determine the domain of the sender.
&'temperror '& Library error or dns error.
&'off '& The DMARC check was disabled for this email.
The Proxy Protocol header is the first data received on a TCP connection
and is inserted before any TLS-on-connect handshake from the client; Exim
negotiates TLS between Exim-as-server and the remote client, not between
-Exim and the proxy server.
+Exim and the proxy server. The Proxy Protocol header must be received
+within &%proxy_protocol_timeout%&, which defaults to 3s.
The following expansion variables are usable
(&"internal"& and &"external"& here refer to the interfaces
# 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
+ defer ratelimit = LIMIT / 5s / per_conn / strict
+ message = Too many connections from this IP right now
.endd
The name is placed in the variable &$event_name$& and the event action
expansion must check this, as it will be called for every possible event type.
-.new
The current list of events is:
-.wen
.display
&`dane:fail after transport `& per connection
&`msg:complete after main `& per message
git://git.exim.org / users / heiko / exim.git / blobdiff