.set I " "
.macro copyyear
-2019
+2020
.endmacro
. /////////////////////////////////////////////////////////////////////////////
of domains that it defines.
.next
.vindex "&$local_part_prefix$&"
+.vindex "&$local_part_prefix_v$&"
.vindex "&$local_part$&"
.vindex "&$local_part_suffix$&"
+.vindex "&$local_part_suffix_v$&"
.cindex affix "router precondition"
If the &%local_parts%& option is set, the local part of the address must be in
the set of local parts that it defines. If &%local_part_prefix%& or
&%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)
-that uses the variables &$local_part$&, &$local_part_prefix$&, and
-&$local_part_suffix$& as necessary.
+.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%&"
This option is not intended for use by external callers. It is used internally
.vitem &%-MG%&&~<&'queue&~name'&>&~<&'message&~id'&>&~<&'message&~id'&>&~...
.oindex "&%-MG%&"
.cindex queue named
-.cindex "named queues"
+.cindex "named queues" "moving messages"
.cindex "queue" "moving messages"
This option requests that each listed message be moved from its current
queue to the given named queue.
.vitem &%-odqs%&
.oindex "&%-odqs%&"
.cindex "SMTP" "delaying delivery"
+.cindex "first pass routing"
This option is a hybrid between &%-odb%&/&%-odi%& and &%-odq%&.
However, like &%-odb%& and &%-odi%&, this option has no effect if
&%queue_only_override%& is false and one of the queueing options in the
.cindex "queue" "double scanning"
.cindex "queue" "routing"
.cindex "routing" "whole queue before delivery"
+.cindex "first pass routing"
An option starting with &%-qq%& requests a two-stage queue run. In the first
stage, the queue is scanned as if the &%queue_smtp_domains%& option matched
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.
+.wen
+
.cindex "hints database" "remembering routing"
The hints database that remembers which messages are waiting for specific hosts
is updated, as if delivery to those hosts had been deferred. After this is
.vitem &%-q[q][i][f[f]][l][G<name>[/<time>]]]%&
.oindex "&%-qG%&"
.cindex queue named
-.cindex "named queues"
+.cindex "named queues" "deliver from"
.cindex "queue" "delivering specific messages"
If the &'G'& flag and a name is present, the queue runner operates on the
queue with the given name rather than the default queue.
.code
local_delivery:
driver = appendfile
- file = /var/mail/$local_part
+ file = /var/mail/$local_part_verified
delivery_date_add
envelope_to_add
return_path_add
# mode = 0660
.endd
This &(appendfile)& transport is used for local delivery to user mailboxes in
-traditional BSD mailbox format. By default it runs under the uid and gid of the
+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 &$local_part_verified$&,
+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_&
directory. Some systems use the alternative approach of running mail deliveries
under a particular group instead of using the sticky bit. The commented options
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
.next
.cindex "query-style lookup" "definition of"
The &'query-style'& type accepts a generalized database query. No particular
.next
.cindex "lookup" "dsearch"
.cindex "dsearch lookup type"
-&(dsearch)&: The given file must be a directory; 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, the result of
-the lookup is the name of the entry, which may be a file, directory,
-symbolic link, or any other kind of directory entry. An example of how this
+&(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.
+
+Options for the lookup can be given by appending them after the word "dsearch",
+separated by a comma. Options, if present, are a comma-separated list having
+each element starting with a tag name and an equals.
+
+Two options are supported, for the return value and for filtering match
+candidates.
+The "ret" option requests an alternate result value of
+the entire path for the entry. Example:
+.code
+${lookup {passwd} dsearch,ret=full {/etc}}
+.endd
+The default result is just the requested entry.
+The "filter" option requests that only directory entries of a given type
+are matched. The match value is one of "file", "dir" or "subdir" (the latter
+not matching "." or ".."). Example:
+.code
+${lookup {passwd} dsearch,filter=file {/etc}}
+.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
&<<SECTvirtualdomains>>&.
.next
.next
.cindex "sqlite lookup type"
.cindex "lookup" "sqlite"
-&(sqlite)&: The format of the query is a filename followed by an SQL statement
+&(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>>&.
.next
or &%redis_servers%&
option (as appropriate) must be set to a colon-separated list of server
information.
+.oindex &%mysql_servers%&
+.oindex &%pgsql_servers%&
+.oindex &%oracle_servers%&
+.oindex &%ibase_servers%&
+.oindex &%redis_servers%&
(For MySQL and PostgreSQL, the global option need not be set if all
queries contain their own server information &-- see section
&<<SECTspeserque>>&.)
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 starting the query with
+done by appending a comma-separated option to the query type:
.display
-&`servers=`&&'server1:server2:server3:...'&&`;`&
.endd
+&`,servers=`&&'server1:server2:server3:...'&
+.wen
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
.endd
In an updating lookup, you could then write:
.code
-${lookup mysql{servers=master; UPDATE ...} }
+${lookup mysql,servers=master {UPDATE ...} }
.endd
That query would then be sent only to the master server. If, on the other hand,
the master is not to be used for reading, and so is not present in the global
option, you can still update it by a query of this form:
.code
-${lookup pgsql{servers=master/db/name/pw; UPDATE ...} }
+${lookup pgsql,servers=master/db/name/pw {UPDATE ...} }
.endd
+.new
+An older syntax places the servers speciification before the qury,
+semicolon separated:
+.code
+${lookup mysql{servers=master; UPDATE ...} }
+.endd
+The new version avoids potential issues with tainted
+arguments in the query, for explicit expansion.
+&*Note*&: server specifications in list-style lookups are still problematic.
+.wen
+
.section "Special MySQL features" "SECID73"
For MySQL, an empty host name or the use of &"localhost"& in &%mysql_servers%&
.cindex "sqlite lookup type"
SQLite is different to the other SQL lookups because a filename is required in
addition to the SQL query. An SQLite database is a single file, and there is no
-daemon as in the other SQL databases. The interface to Exim requires the name
-of the file, as an absolute path, to be given at the start of the query. It is
-separated from the query by white space. This means that the path name cannot
-contain white space. Here is a lookup expansion example:
+daemon as in the other SQL databases.
+
+.new
+.oindex &%sqlite_dbfile%&
+The preferred way of specifying the file is by using the
+&%sqlite_dbfile%& option, set to
+an absolute path.
+.wen
+A deprecated method is available, prefixing the query with the filename
+separated by white space.
+This means that the path name cannot contain white space.
+.cindex "tainted data" "sqlite file"
+It also means that the query cannot use any tainted values, as that taints
+the entire query including the filename - resulting in a refusal to open
+the file.
+
+.new
+Here is a lookup expansion example:
.code
-${lookup sqlite {/some/thing/sqlitedb \
- select name from aliases where id='userx';}}
+sqlite_dbfile = /some/thing/sqlitedb
+...
+${lookup sqlite {select name from aliases where id='userx';}}
.endd
In a list, the syntax is similar. For example:
.code
-domainlist relay_to_domains = sqlite;/some/thing/sqlitedb \
+domainlist relay_to_domains = sqlite;\
select * from relays where ip='$sender_host_address';
.endd
+.wen
The only character affected by the &%quote_sqlite%& operator is a single
quote, which it doubles.
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
+accessing databases. To stop non-admin users from using the &%-bP%& command
+line option to read these values, you can precede the definition with the
+word &"hide"&. For example:
+.code
+hide domainlist filter_for_domains = ldap;PASS=secret ldap::/// ...
+.endd
+.wen
+
+
Named lists may have a performance advantage. When Exim is routing an
address or checking an incoming message, it caches the result of tests on named
lists. So, if you have a setting such as
&%domains%& option on a router, the data is preserved in the &$domain_data$&
variable and can be referred to in other options.
.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 command 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"
If none of the above cases apply, a caseless textual comparison is made
between the pattern and the domain.
"&*$bheader_*&<&'header&~name'&>&*:*&&~or&~&&&
&*$bh_*&<&'header&~name'&>&*:*&" &&&
"&*$lheader_*&<&'header&~name'&>&*:*&&~or&~&&&
- &*$lh_*&<&'header&~name'&>&*:*&"
+ &*$lh_*&<&'header&~name'&>&*:*&" &&&
"&*$rheader_*&<&'header&~name'&>&*:*&&~or&~&&&
&*$rh_*&<&'header&~name'&>&*:*&"
.cindex "expansion" "header insertion"
those headers that contain lists of addresses, a comma is also inserted at the
junctions between headers. This does not happen for the &%rheader%& expansion.
+.new
+.cindex "tainted data"
+When the headers are from an incoming message,
+the result of expanding any of these variables is tainted.
+.wen
+
.vitem &*${hmac{*&<&'hashname'&>&*}{*&<&'secret'&>&*}{*&<&'string'&>&*}}*&
.cindex "expansion" "hmac hashing"
.endd
The third argument is a list of options, of which the first element is the timeout
-and must be present if the argument is given.
+and must be present if any options are given.
Further elements are options of form &'name=value'&.
-Two option types is currently recognised: shutdown and tls.
-The first defines whether (the default)
-or not a shutdown is done on the connection after sending the request.
-Example, to not do so (preferred, eg. by some webservers):
+Example:
.code
${readsocket{/socket/name}{request string}{3s:shutdown=no}}
.endd
-The second, tls, controls the use of TLS on the connection. Example:
-.code
-${readsocket{/socket/name}{request string}{3s:tls=yes}}
-.endd
-The default is to not use TLS.
+
+.new
+The following option names are recognised:
+.ilist
+&*cache*&
+Defines if the result data can be cached for use by a later identical
+request in the same process.
+Values are &"yes"& or &"no"& (the default).
+If not, all cached results for this connection specification
+will be invalidated.
+
+.next
+&*shutdown*&
+Defines whether or not a write-shutdown is done on the connection after
+sending the request. Values are &"yes"& (the default) or &"no"&
+(preferred, eg. by some webservers).
+
+.next
+&*tls*&
+Controls the use of TLS on the connection.
+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
that is read, in the same way as for &%readfile%& (see above). This example
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.
+See also &$domain_verified$&.
+.wen
+
.vitem &$domain_data$&
.vindex "&$domain_data$&"
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.
+
+&*Warning*&: the content of this variable is usually provided by a potential
+attacker.
+Consider carefully the implications of using it unvalidated as a name
+for file access.
+This presents issues for users' &_.forward_& and filter files.
+For traditional full user accounts, use &%check_local_users%& and the
+&$local_part_verified$& variable rather than this one.
+For virtual users, store a suitable pathname component in the database
+which is used for account name validation, and use that retrieved value
+rather than this variable.
+If needed, use a router &%address_data%& or &%set%& option for
+the retrieved data.
+.wen
+
.vindex "&$local_part_prefix$&"
+.vindex "&$local_part_prefix_v$&"
.vindex "&$local_part_suffix$&"
+.vindex "&$local_part_suffix_v$&"
.cindex affix variables
If a local part prefix or suffix has been recognized, it is not included in the
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
+If the affix specification included a wildcard then the portion of
+the affix matched by the wildcard is in
+&$local_part_prefix_v$& or &$local_part_suffix_v$& as appropriate.
+.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
specific prefix for the local part was recognized, it is available in this
variable, having been removed from &$local_part$&.
+.new
+.vitem &$local_part_prefix_v$&
+.vindex "&$local_part_prefix_v$&"
+When &$local_part_prefix$& is valid and the prefix match used a wildcard,
+the portion matching the wildcard is available in this variable.
+.wen
+
.vitem &$local_part_suffix$&
.vindex "&$local_part_suffix$&"
When an address is being routed or delivered, and a
specific suffix for the local part was recognized, it is available in this
variable, having been removed from &$local_part$&.
+.new
+.vitem &$local_part_suffix_v$&
+.vindex "&$local_part_suffix_v$&"
+When &$local_part_suffix$& is valid and the suffix match used a wildcard,
+the portion matching the wildcard is available in this variable.
+.wen
+
+.new
+.vitem &$local_part_verified$&
+.vindex "&$local_part_verified$&"
+If the router generic option &%check_local_part%& has run successfully,
+this variable has the user database version of &$local_part$&.
+Such values are not tainted and hence usable for building file names.
+.wen
+
.vitem &$local_scan_data$&
.vindex "&$local_scan_data$&"
This variable contains the text returned by the &[local_scan()]& function when
.vitem &$queue_name$&
.vindex &$queue_name$&
-.cindex "named queues"
+.cindex "named queues" variable
.cindex queues named
The name of the spool queue in use; empty for the default queue.
+.vitem &$queue_size$&
+.vindex "&$queue_size$&"
+.cindex "queue" "size of"
+.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.
+
.vitem &$r_...$&
.vindex &$r_...$&
.cindex router variables
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.
+Provided that you do trust the resolver (ie, is on localhost) you can tell
+glibc to pass through any successful validation with a new option in
+&_/etc/resolv.conf_&:
+.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).
.row &%daemon_startup_sleep%& "time to sleep between tries"
.row &%extra_local_interfaces%& "not necessarily listened on"
.row &%local_interfaces%& "on which to listen, with optional ports"
+.row &%notifier_socket%& "override compiled-in value"
.row &%pid_file_path%& "override compiled-in value"
.row &%queue_run_max%& "maximum simultaneous queue runners"
.endtable
.table2
.row &%dkim_verify_hashes%& "DKIM hash methods accepted for signatures"
.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 &%host_lookup%& "host name looked up for these hosts"
.row &%host_lookup_order%& "order of DNS and local name lookups"
and an order of processing.
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
first success.
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.
+Provided that you do trust the resolver (ie, is on localhost) you can tell
+glibc to pass through any successful validation with a new option in
+&_/etc/resolv.conf_&:
+.code
+options trust-ad
+.endd
+.wen
+
.option dns_ipv4_lookup main "domain list&!!" unset
.cindex "IPv6" "DNS lookup for AAAA records"
transport driver.
+.new
+.option notifier_socket main string "$spool_directory/exim_daemon_notify"
+This option gives the name for a unix-domain socket on which the daemon
+listens for work and information-requests.
+Only installations running multiple daemons sharing a spool directory
+should need to modify the default.
+
+The option is expanded before use.
+If the platform supports Linux-style abstract socket names, the result
+is used with a nul byte prefixed.
+Otherwise, it should be a full path name and use a directory accessible
+to Exim.
+
+If the Exim command line uses a &%-oX%& option and does not use &%-oP%&
+then a notifier socket is not created.
+.wen
+
+
.option openssl_options main "string list" "+no_sslv2 +no_sslv3 +single_dh_use +no_ticket +no_renegotiation"
.cindex "OpenSSL "compatibility options"
This option allows an administrator to adjust the SSL options applied
the daemon's command line.
.cindex queues named
-.cindex "named queues"
+.cindex "named queues" "resource limit"
To set limits for different named queues use
an expansion depending on the &$queue_name$& variable.
.option queue_smtp_domains main "domain list&!!" unset
.cindex "queueing incoming messages"
.cindex "message" "queueing remote deliveries"
+.cindex "first pass routing"
When this option is set, a delivery process is started whenever a message is
received, routing is performed, and local deliveries take place.
However, if any SMTP deliveries are required for domains that match
${if def:sender_helo_name {(helo=$sender_helo_name)\n\t}}}}\
by $primary_hostname \
${if def:received_protocol {with $received_protocol }}\
- ${if def:tls_ver { ($tls_ver)}}\
+ ${if def:tls_in_ver { ($tls_in_ver)}}\
${if def:tls_in_cipher_std { tls $tls_in_cipher_std\n\t}}\
(Exim $version_number)\n\t\
${if def:sender_address \
${if def:received_for {\n\tfor $received_for}}
.endd
-The reference to the TLS cipher is omitted when Exim is built without TLS
+The references to the TLS version and cipher are
+omitted when Exim is built without TLS
support. The use of conditional expansions ensures that this works for both
locally generated messages and messages received from remote hosts, giving
header lines such as the following:
smtp_etrn_command = /etc/etrn_command $domain \
$sender_host_address
.endd
+.new
+If the option is not set, the argument for the ETRN command must
+be a &'#'& followed by an address string.
+In this case an &'exim -R <string>'& command is used;
+if the ETRN ACL has set up a named-queue then &'-MCG <queue>'& is appended.
+.wen
+
A new process is created to run the command, but Exim does not wait for it to
complete. Consequently, its status cannot be checked. If the command cannot be
run, a line is written to the panic log, but the ETRN caller still receives
This option specifies a list of text headers,
colon-separated (by default, changeable in the usual way &<<SECTlistsepchange>>&),
that is associated with any addresses that are accepted by the router.
-Each item is separately expanded, at routing time. However, this
-option has no effect when an address is just being verified. The way in which
+However, the option has no effect when an address is just being verified.
+Each list item is separately expanded, at transport time.
+.new
+If an item ends in *, it will match any header with the given prefix.
+.wen
+The way in which
the text is used to remove header lines at transport time is described in
section &<<SECTheadersaddrem>>&. Header lines are not actually removed until
the message is in the process of being transported. This means that references
to header lines in string expansions in the transport's configuration still
&"see"& the original header lines.
-The &%headers_remove%& option is expanded after &%errors_to%& and
+The &%headers_remove%& option is handled after &%errors_to%& and
&%headers_add%&, but before &%transport%&. If an item expansion is forced to fail,
the item has no effect. Other expansion failures are treated as configuration
errors.
This behaviour can be overridden by setting &%rcpt_include_affixes%& true on
the relevant transport.
+.new
+.vindex &$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$&.
+.wen
+
When an address is being verified, &%local_part_prefix%& affects only the
behaviour of the router. If the callout feature of verification is in use, this
means that the full address, including the prefix, will be used during the
.section "Format of one host item" "SECTformatonehostitem"
-Each item in the list of hosts is either a host name or an IP address,
-optionally with an attached port number. When no port is given, an IP address
+Each item in the list of hosts can be either a host name or an IP address,
+optionally with an attached port number, or it can be a single "+"
+(see &%hosts_randomize%&).
+When no port is given, an IP address
is not enclosed in brackets. When a port is specified, it overrides the port
specification on the transport. The port is separated from the name or address
by a colon. This leads to some complications:
yield empty addresses, for example, items containing only RFC 2822 address
comments.
+.new
+.cindex "tainted data" "in filenames"
+.cindex redirect "tainted data"
+Tainted data may not be used for a filename.
+
+&*Warning*&: It is unwise to use &$local_part$& or &$domain$&
+directly for redirection,
+as they are provided by a potential attacker.
+In the examples above, &$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$&).
+.wen
+
.section "Forward files and address verification" "SECID125"
.code
list1: :include:/opt/lists/list1
.endd
+.new
+.cindex "tainted data" "in filenames"
+.cindex redirect "tainted data"
+Tainted data may not be used for a filename.
+.wen
.next
.cindex "address redirection" "to black hole"
.cindex "delivery" "discard"
.option headers_remove transports list&!! unset
.cindex "header lines" "removing"
.cindex "transport" "header lines; removing"
-This option specifies a list of header names,
-colon-separated (by default, changeable in the usual way &<<SECTlistsepchange>>&);
-these headers are omitted from the message as it is transported, as described
-in section &<<SECTheadersaddrem>>&. Header removal can also be specified by
-routers.
+This option specifies a list of text headers,
+colon-separated (by default, changeable in the usual way &<<SECTlistsepchange>>&),
+to be removed from the message.
+However, the option has no effect when an address is just being verified.
Each list item is separately expanded.
If the result of the expansion is an empty string, or if the expansion
is forced to fail, no action is taken. Other expansion failures are treated as
errors and cause the delivery to be deferred.
+.new
+If an item ends in *, it will match any header with the given prefix.
+.wen
+
+Matching headers are omitted from the message as it is transported, as described
+in section &<<SECTheadersaddrem>>&. Header removal can also be specified by
+routers.
Unlike most options, &%headers_remove%& can be specified multiple times
for a transport; all listed headers are removed.
used to determine the file or directory name for the delivery. Normally, the
contents of &$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"
If two messages arrive at almost the same time, and both are routed to a pipe
.section "The PLAIN authentication mechanism" "SECID172"
.cindex "PLAIN authentication mechanism"
-.cindex "authentication" "PLAIN mechanism"
+.cindex authentication PLAIN
.cindex "binary zero" "in &(plaintext)& authenticator"
The PLAIN authentication mechanism (RFC 2595) specifies that three strings be
sent as one item of data (that is, one combined string containing two NUL
.section "The LOGIN authentication mechanism" "SECID173"
.cindex "LOGIN authentication mechanism"
-.cindex "authentication" "LOGIN mechanism"
+.cindex authentication LOGIN
The LOGIN authentication mechanism is not documented in any RFC, but is in use
in a number of programs. No data is sent with the AUTH command. Instead, a
user name and password are supplied separately, in response to prompts. The
.scindex IIDcramauth1 "&(cram_md5)& authenticator"
.scindex IIDcramauth2 "authenticators" "&(cram_md5)&"
.cindex "CRAM-MD5 authentication mechanism"
-.cindex "authentication" "CRAM-MD5 mechanism"
+.cindex authentication CRAM-MD5
The CRAM-MD5 authentication mechanism is described in RFC 2195. The server
sends a challenge string to the client, and the response consists of a user
name and the CRAM-MD5 digest of the challenge string combined with a secret
.scindex IIDdcotauth1 "&(dovecot)& authenticator"
.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.
+Dovecot 2 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
connection, a client certificate has been verified, the &"valid-client-cert"&
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
+conf.d/10-master.conf :-
+
+service auth {
+...
+#SASL
+ unix_listener auth-client {
+ mode = 0660
+ user = mail
+ }
+...
+}
+
+conf.d/10-auth.conf :-
+
+auth_mechanisms = plain login ntlm
+.endd
+.wen
+
.ecindex IIDdcotauth1
.ecindex IIDdcotauth2
.cindex "authentication" "LOGIN"
.cindex "authentication" "DIGEST-MD5"
.cindex "authentication" "CRAM-MD5"
-.cindex "authentication" "SCRAM-SHA-1"
-The &(gsasl)& authenticator provides server integration for the GNU SASL
+.cindex "authentication" "SCRAM family"
+The &(gsasl)& authenticator provides integration for the GNU SASL
library and the mechanisms it provides. This is new as of the 4.80 release
and there are a few areas where the library does not let Exim smoothly
scale to handle future authentication mechanisms, so no guarantee can be
made that any particular new authentication mechanism will be supported
without code changes in Exim.
-Exim's &(gsasl)& authenticator does not have client-side support at this
-time; only the server-side support is implemented. Patches welcome.
+.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
+when this happens.
+
+
+.option client_authz gsasl string&!! unset
+This option can be used to supply an &'authorization id'&
+which is different to the &'authentication_id'& provided
+by &%client_username%& option.
+If unset or (after expansion) empty it is not used,
+which is the common case.
+
+.option client_channelbinding gsasl boolean false
+See &%server_channelbinding%& below.
+
+.option client_password gsasl string&!! unset
+This option is exapanded before use, and should result in
+the password to be used, in clear.
+
+.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%&.
+The value after expansion should be
+a 40 (for SHA-1) or 64 (for SHA-256) character string
+with the PBKDF2-prepared password, hex-encoded.
+Note that this value will depend on the salt and iteration-count
+supplied by the server.
+.wen
+
.option server_channelbinding gsasl boolean false
-Do not set this true without consulting a cryptographic engineer.
+Do not set this true and rely on the properties
+without consulting a cryptographic engineer.
Some authentication mechanisms are able to use external context at both ends
of the session to bind the authentication to that context, and fail the
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
of Exim might have switched the default to be true.
-However, Channel Binding in TLS has proven to be broken in current versions.
+However, Channel Binding in TLS has proven to be vulnerable in current versions.
Do not plan to rely upon this feature for security, ever, without consulting
with a subject matter expert (a cryptographic engineer).
Some mechanisms will use this data.
-.option server_scram_iter gsasl string&!! unset
+.option server_scram_iter gsasl string&!! 4096
This option provides data for the SCRAM family of mechanisms.
-&$auth1$& is not available at evaluation time.
-(This may change, as we receive feedback on use)
-
+.new
+The &$auth1$&, &$auth2$& and &$auth3$& variables are available
+when this option is expanded.
+
+The result of expansion should be a decimal number,
+and represents both a lower-bound on the security, and
+a compute cost factor imposed on the client
+(if it does not cache results, or the server changes
+either the iteration count or the salt).
+A minimum value of 4096 is required by the standards
+for all current SCRAM mechanism variants.
+.wen
.option server_scram_salt gsasl string&!! unset
This option provides data for the SCRAM family of mechanisms.
-&$auth1$& is not available at evaluation time.
-(This may change, as we receive feedback on use)
+.new
+The &$auth1$&, &$auth2$& and &$auth3$& variables are available
+when this option is expanded.
+The value should be a base64-encoded string,
+of random data typically 4-to-16 bytes long.
+If unset or empty after expansion the library will provides a value for the
+protocol conversation.
+.wen
+
+
+.new
+.option server_key gsasl string&!! unset
+.option server_skey gsasl string&!! unset
+These options can be used for the SCRAM family of mechanisms
+to provide stored information related to a password,
+the storage of which is preferable to plaintext.
+
+&%server_key%& is the value defined in the SCRAM standards as ServerKey;
+&%server_skey%& is StoredKey.
+
+They are only available for version 1.9.0 (or later) of the gsasl library.
+When this is so, the macros
+_OPT_AUTHENTICATOR_GSASL_SERVER_KEY
+and _HAVE_AUTH_GSASL_SCRAM_S_KEY
+will be defined.
+
+The &$authN$& variables are available when these options are expanded.
+
+If set, the results of expansion should for each
+should be a 28 (for SHA-1) or 44 (for SHA-256) character string
+of base64-coded data, and will be used in preference to the
+&%server_password%& option.
+If unset or not of the right length, &%server_password%& will be used.
+
+The libgsasl library release includes a utility &'gsasl'& which can be used
+to generate these values.
+.wen
.option server_service gsasl string &`smtp`&
It can be at the end of an &%accept%& statement:
.code
accept ...some conditions
- control = queue_only
+ control = queue
.endd
In this case, the control is applied when this statement yields &"accept"&, in
other words, when the conditions are all true.
It can be in the middle of an &%accept%& statement:
.code
accept ...some conditions...
- control = queue_only
+ control = queue
...some more conditions...
.endd
If the first set of conditions are true, the control is applied, even if the
the operation and configuration of DKIM, see section &<<SECDKIM>>&.
+.vitem &*control&~=&~dmarc_disable_verify*&
+.cindex "disable DMARC verify"
+.cindex "DMARC" "disable verify"
+This control turns off DMARC verification processing entirely. For details on
+the operation and configuration of DMARC, see section &<<SECDMARC>>&.
+
+
.vitem &*control&~=&~dscp/*&<&'value'&>
.cindex "&ACL;" "setting DSCP value"
.cindex "DSCP" "inbound"
controlled by &%acl_smtp_connect%& or &%acl_smtp_helo%&. See also
&%pipelining_advertise_hosts%&.
-.vitem &*control&~=&~queue_only*&
+.new
+.vitem &*control&~=&~queue/*&<&'options'&>* &&&
+ &*control&~=&~queue_only*&
+.oindex "&%queue%&"
.oindex "&%queue_only%&"
.cindex "queueing incoming messages"
+.cindex queueing "forcing in ACL"
+.cindex "first pass routing"
This control is permitted only for the MAIL, RCPT, DATA, and non-SMTP ACLs, in
other words, only when a message is being received. If the message is accepted,
it is placed on Exim's queue and left there for delivery by a subsequent queue
-runner. No immediate delivery process is started. In other words, it has the
-effect as the &%queue_only%& global option. However, the control applies only
-to the current message, not to any subsequent ones that may be received in the
-same SMTP connection.
+runner.
+If used with no options set,
+no immediate delivery process is started. In other words, it has the
+effect as the &%queue_only%& global option or &'-odq'& command-line option.
+
+If the &'first_pass_route'& option is given then
+the behaviour is like the command-line &'-oqds'& option;
+a delivery process is started which stops short of making
+any SMTP delivery. The benefit is that the hints database will be updated for
+the message being waiting for a specific host, and a later queue run will be
+able to send all such messages on a single connection.
+
+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"
available in the MIME ACL:
.vlist
+.vitem &$mime_anomaly_level$& &&&
+ &$mime_anomaly_text$&
+.vindex &$mime_anomaly_level$&
+.vindex &$mime_anomaly_text$&
+If there are problems decoding, these variables contain information on
+the detected issue.
+
.vitem &$mime_boundary$&
-If the current part is a multipart (see &$mime_is_multipart$&) below, it should
+.vindex &$mime_boundary$&
+If the current part is a multipart (see &$mime_is_multipart$& below), it should
have a boundary string, which is stored in this variable. If the current part
has no boundary parameter in the &'Content-Type:'& header, this variable
contains the empty string.
.vitem &$mime_charset$&
+.vindex &$mime_charset$&
This variable contains the character set identifier, if one was found in the
&'Content-Type:'& header. Examples for charset identifiers are:
.code
case-insensitively.
.vitem &$mime_content_description$&
+.vindex &$mime_content_description$&
This variable contains the normalized content of the &'Content-Description:'&
header. It can contain a human-readable description of the parts content. Some
implementations repeat the filename for attachments here, but they are usually
only used for display purposes.
.vitem &$mime_content_disposition$&
+.vindex &$mime_content_disposition$&
This variable contains the normalized content of the &'Content-Disposition:'&
header. You can expect strings like &"attachment"& or &"inline"& here.
.vitem &$mime_content_id$&
+.vindex &$mime_content_id$&
This variable contains the normalized content of the &'Content-ID:'& header.
This is a unique ID that can be used to reference a part from another part.
.vitem &$mime_content_size$&
+.vindex &$mime_content_size$&
This variable is set only after the &%decode%& modifier (see above) has been
successfully run. It contains the size of the decoded part in kilobytes. The
size is always rounded up to full kilobytes, so only a completely empty part
has a &$mime_content_size$& of zero.
.vitem &$mime_content_transfer_encoding$&
+.vindex &$mime_content_transfer_encoding$&
This variable contains the normalized content of the
&'Content-transfer-encoding:'& header. This is a symbolic name for an encoding
type. Typical values are &"base64"& and &"quoted-printable"&.
.vitem &$mime_content_type$&
+.vindex &$mime_content_type$&
If the MIME part has a &'Content-Type:'& header, this variable contains its
value, lowercased, and without any options (like &"name"& or &"charset"&). Here
are some examples of popular MIME types, as they may appear in this variable:
empty string.
.vitem &$mime_decoded_filename$&
+.vindex &$mime_decoded_filename$&
This variable is set only after the &%decode%& modifier (see above) has been
successfully run. It contains the full path and filename of the file
containing the decoded data.
.cindex "RFC 2047"
.vlist
.vitem &$mime_filename$&
+.vindex &$mime_filename$&
This is perhaps the most important of the MIME variables. It contains a
proposed filename for an attachment, if one was found in either the
&'Content-Type:'& or &'Content-Disposition:'& headers. The filename will be
found, this variable contains the empty string.
.vitem &$mime_is_coverletter$&
+.vindex &$mime_is_coverletter$&
This variable attempts to differentiate the &"cover letter"& of an e-mail from
attached data. It can be used to clamp down on flashy or unnecessarily encoded
content in the cover letter, while not restricting attachments at all.
condition = $mime_is_coverletter
condition = ${if eq{$mime_content_type}{text/html}{1}{0}}
.endd
+
.vitem &$mime_is_multipart$&
+.vindex &$mime_is_multipart$&
This variable has the value 1 (true) when the current part has the main type
&"multipart"&, for example, &"multipart/alternative"& or &"multipart/mixed"&.
Since multipart entities only serve as containers for other parts, you may not
want to carry out specific actions on them.
.vitem &$mime_is_rfc822$&
+.vindex &$mime_is_rfc822$&
This variable has the value 1 (true) if the current part is not a part of the
checked message itself, but part of an attached message. Attached message
decoding is fully recursive.
.vitem &$mime_part_count$&
+.vindex &$mime_part_count$&
This variable is a counter that is raised for each processed MIME part. It
starts at zero for the very first part (which is usually a multipart). The
counter is per-message, so it is reset when processing RFC822 attachments (see
HAVE_LOCAL_SCAN=yes
LOCAL_SCAN_SOURCE=Local/local_scan.c
.endd
-for example. The function must be called &[local_scan()]&. It is called by
+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
function controls whether the message is actually accepted or not. There is a
.cindex &%dlfunc%& "API description"
You must include this line near the start of your code:
.code
+#define LOCAL_SCAN
#include "local_scan.h"
.endd
This header file defines a number of variables and other values, and the
prototype for the function itself. Exim is coded to use unsigned char values
almost exclusively, and one of the things this header defines is a shorthand
for &`unsigned char`& called &`uschar`&.
-It also contains the following macro definitions, to simplify casting character
+It also makes available the following macro definitions, to simplify casting character
strings and pointers to character strings:
.code
#define CS (char *)
arguments. It flushes the output stream, and returns a non-zero value if there
is an error.
-.vitem &*void&~*store_get(int)*&
+.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 argument. Exim bombs out if it ever
+chunk of memory whose size is given by the first argument.
+The second argument should be given as TRUE if the memory will be used for
+data possibly coming from an attacker (eg. the message content),
+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)*&
+.vitem &*void&~*store_get_perm(int,BOOL)*&
This function is like &'store_get()'&, but it always gets memory from the
permanent pool. See the next section for a discussion of memory handling.
virtual:
driver = redirect
domains = dsearch;/etc/mail/virtual
- data = ${lookup{$local_part}lsearch{/etc/mail/virtual/$domain}}
+ data = ${lookup{$local_part}lsearch{/etc/mail/virtual/$domain_data}}
no_more
.endd
+.new
The &%domains%& option specifies that the router is to be skipped, unless there
is a file in the &_/etc/mail/virtual_& directory whose name is the same as the
-domain that is being processed. When the router runs, it looks up the local
+domain that is being processed.
+The &(dsearch)& lookup used results in an untainted version of &$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%&
setting ensures that if the lookup fails (leading to &%data%& being an empty
string), Exim gives up on the address without trying any subsequent routers.
.cindex "SMTP" "passed connection"
.cindex "SMTP" "multiple deliveries"
.cindex "multiple SMTP deliveries"
+.cindex "first pass routing"
Mail waiting to be sent from an intermittently connected host will probably
not have been routed, because without a connection DNS lookups are not
possible. This means that if a normal queue run is done at connection time,
&`DKIM`& domain verified in incoming message
&`DN `& distinguished name from peer certificate
&`DS `& DNSSEC secured lookups
-&`DT `& on &`=>`& lines: time taken for a delivery
+&`DT `& on &`=>`&, &'=='& and &'**'& lines: time taken for, or to attempt, a delivery
&`F `& sender address (on delivery lines)
&`H `& host name and IP address
&`I `& local interface used
&` arguments `& command line arguments
&`*connection_reject `& connection rejections
&`*delay_delivery `& immediate delivery delayed
-&` deliver_time `& time taken to perform delivery
+&` deliver_time `& time taken to attempt delivery
&` delivery_size `& add &`S=`&&'nnn'& to => lines
&`*dkim `& DKIM verified domain on <= lines
&` dkim_verbose `& separate full DKIM verification result line, per signature
openssl genrsa -out dkim_rsa.private 2048
openssl rsa -in dkim_rsa.private -out /dev/stdout -pubout -outform PEM
.endd
+The result file from the first command should be retained, and
+this option set to use it.
Take the base-64 lines from the output of the second command, concatenated,
for the DNS TXT record.
See section 3.6 of RFC6376 for the record specification.
.option dkim_strict smtp string&!! unset
This option defines how Exim behaves when signing a message that
should be signed fails for some reason. When the expansion evaluates to
-either "1" or "true", Exim will defer. Otherwise Exim will send the message
+either &"1"& or &"true"&, Exim will defer. Otherwise Exim will send the message
unsigned. You can use the &%$dkim_domain%& and &%$dkim_selector%& expansion
variables here.
When unspecified, the header names listed in RFC4871 will be used,
whether or not each header is present in the message.
The default list is available for the expansion in the macro
-"_DKIM_SIGN_HEADERS".
+&"_DKIM_SIGN_HEADERS"&
+.new
+and an oversigning variant is in &"_DKIM_OVERSIGN_HEADERS"&.
+.wen
If a name is repeated, multiple headers by that name (or the absence thereof)
will be signed. The textually later headers in the headers part of the
message are signed first, if there are multiples.
-A name can be prefixed with either an '=' or a '+' character.
-If an '=' prefix is used, all headers that are present with this name
+A name can be prefixed with either an &"="& or a &"+"& character.
+If an &"="& prefix is used, all headers that are present with this name
will be signed.
-If a '+' prefix if used, all headers that are present with this name
+If a &"+"& prefix if used, all headers that are present with this name
will be signed, and one signature added for a missing header with the
name will be appended.
.vitem &%$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
less than 1024 bits as valid signatures.
.endd
-To enforce this you must have a DKIM ACL which checks this variable
-and overwrites the &$dkim_verify_status$& variable as discussed above.
-As EC keys are much smaller, the check should only do this for RSA keys.
+This is enforced by the default setting for the &%dkim_verify_min_keysizes%&
+option.
.endlist
top level domains the opendmarc library uses
during domain parsing. Maintained by Mozilla,
the most current version can be downloaded
-from a link at &url(https://publicsuffix.org/list/, currently pointing
-at https://publicsuffix.org/list/public_suffix_list.dat)
-See also util/renew-opendmarc-tlds.sh script.
-The default for the option is /etc/exim/opendmarc.tlds.
+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
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
+&`msg:defer after transport `& per message per delivery try
&`msg:delivery after transport `& per recipient
&`msg:rcpt:host:defer after transport `& per recipient per host
&`msg:rcpt:defer after transport `& per recipient
-&`msg:host:defer after transport `& per attempt
+&`msg:host:defer after transport `& per host per delivery try; host errors
&`msg:fail:delivery after transport `& per recipient
&`msg:fail:internal after main `& per recipient
&`tcp:connect before transport `& per connection
with the event type:
.display
&`dane:fail `& failure reason
+&`msg:defer `& error string
&`msg:delivery `& smtp confirmation message
&`msg:fail:internal `& failure reason
&`msg:fail:delivery `& smtp error message
+&`msg:host:defer `& error string
&`msg:rcpt:host:defer `& error string
&`msg:rcpt:defer `& error string
-&`msg:host:defer `& error string
&`tls:cert `& verification chain depth
&`smtp:connect `& smtp banner
&`smtp:ehlo `& smtp ehlo response
git://git.exim.org / users / jgh / exim.git / blobdiff