-. $Cambridge: exim/doc/doc-docbook/spec.xfpt,v 1.2 2006/04/04 14:03:49 ph10 Exp $
+. $Cambridge: exim/doc/doc-docbook/spec.xfpt,v 1.8 2006/07/03 18:11:41 fanf2 Exp $
.
. /////////////////////////////////////////////////////////////////////////////
. This is the primary source of the Exim Manual. It is an xfpt document that is
. /////////////////////////////////////////////////////////////////////////////
.set ACL "access control lists (ACLs)"
-.set previousversion "4.60"
-.set version "4.61"
+.set previousversion "4.61"
+.set version "4.62"
. /////////////////////////////////////////////////////////////////////////////
<bookinfo>
<title>Specification of the Exim Mail Transfer Agent</title>
<titleabbrev>The Exim MTA</titleabbrev>
-<date>22 March 2006</date>
+<date>27 April 2006</date>
<author><firstname>Philip</firstname><surname>Hazel</surname></author>
<authorinitials>PH</authorinitials>
<affiliation><orgname>University of Cambridge Computing Service</orgname></affiliation>
<address>New Museums Site, Pembroke Street, Cambridge CB2 3QH, England</address>
<revhistory><revision>
- <revnumber>4.61</revnumber>
- <date>22 March 2006</date>
+ <revnumber>4.62</revnumber>
+ <date>27 April 2006</date>
<authorinitials>PH</authorinitials>
</revision></revhistory>
<copyright><year>2006</year><holder>University of Cambridge</holder></copyright>
.cindex "spool directory" "&_input_& sub-directory"
By default all these message files are held in a single directory called
&_input_& inside the general Exim spool directory. Some operating systems do
-not perform very well if the number of files in a directory gets very large; to
+not perform very well if the number of files in a directory gets large; to
improve performance in such cases, the &%split_spool_directory%& option can be
used. This causes Exim to split up the input files into 62 sub-directories
-whose names are single letters or digits.
+whose names are single letters or digits. &new("When this is done, the queue is
+processed one sub-directory at a time instead of all at once, which can improve
+overall performance even when there are not enough files in each directory to
+affect file system performance.")
The envelope information consists of the address of the message's sender and
the addresses of the recipients. This information is entirely separate from
exim -brt bach.comp.mus.example
Retry rule: *.comp.mus.example F,2h,15m; F,4d,30m;
.endd
-.new
See chapter &<<CHAPretry>>& for a description of Exim's retry rules. The first
argument, which is required, can be a complete address in the form
&'local_part@domain'&, or it can be just a domain name. If the second argument
exim -brt haydn.comp.mus.example quota_3d
Retry rule: *@haydn.comp.mus.example quota_3d F,1h,15m
.endd
-.wen
.vitem &%-brw%&
.oindex "&%-brw%&"
&`.include`& <&'file name'&>
&`.include_if_exists`& <&'file name'&>
.endd
-.new
on a line by itself. Double quotes round the file name are optional. If you use
the first form, a configuration error occurs if the file does not exist; the
second form does nothing for non-existent files. In all cases, an absolute file
name is required.
-.wen
Includes may be nested to any depth, but remember that Exim reads its
configuration file often, so it is a good idea to keep them to a minimum.
-.section "Main configuration settings"
+.section "Main configuration settings" "SECTdefconfmain"
The main (global) configuration option settings must always come first in the
file. The first thing you'll see in the file, after some initial comments, is
the line
scanner, and the second specifies the interface to SpamAssassin. Further
details are given in chapter &<<CHAPexiscan>>&.
+Three more commented-out option settings follow:
+.code
+# tls_advertise_hosts = *
+# tls_certificate = /etc/ssl/exim.crt
+# tls_privatekey = /etc/ssl/exim.pem
+.endd
+These are example settings that can be used when Exim is compiled with
+support for TLS (aka SSL) as described in &<<SECTinctlsssl>>&. The
+first one specifies the list of clients that are allowed to use TLS
+when connecting to this server; in this case the wildcard means all
+clients. The other options specify where Exim should find its TLS
+certificate and private key, which together prove the server's
+identity to any clients that connect. More details are given in
+&<<CHAPTLS>>&.
+
+Another two commented-out option settings follow:
+.code
+# daemon_smtp_ports = 25 : 465 : 587
+# tls_on_connect_ports = 465
+.endd
+These options provide better support for roaming users who wish to use
+this server for message submission. They are not much use unless you
+have turned on TLS (as described in the previous paragraph) and
+authentication (about which more in &<<SECTdefconfauth>>&). The usual
+SMTP port 25 is often blocked on end-user networks, so RFC 4409
+specifies that message submission should use port 587 instead. However
+some software (notably Microsoft Outlook) cannot be configured to use
+port 587 correctly, so these settings also enable the non-standard
+&"smtps"& port 465.
+
Two more commented-out options settings follow:
.code
# qualify_domain =
The next two lines are concerned with &'ident'& callbacks, as defined by RFC
1413 (hence their names):
+.new
.code
rfc1413_hosts = *
-rfc1413_query_timeout = 30s
+rfc1413_query_timeout = 5s
.endd
+.wen
These settings cause Exim to make ident callbacks for all incoming SMTP calls.
You can limit the hosts to which these calls are made, or change the timeout
that is used. If you set the timeout to zero, all ident calls are disabled.
This statement accepts the address if the client host has authenticated itself.
Submission mode is again specified, on the grounds that such messages are most
likely to come from MUAs. The default configuration does not define any
-authenticators, which means that no client can in fact authenticate. You will
-need to add authenticator definitions if you want to make use of this ACL
-statement.
+authenticators, though it does include some nearly complete commented-out
+examples described in &<<SECTdefconfauth>>&. This means that no client can in
+fact authenticate until you complete the authenticator definitions.
.code
# deny message = rejected because $sender_host_address \
# is in a black list at $dnslist_domain\n\
-.section "Authenticators configuration"
+.section "Authenticators configuration" "SECTdefconfauth"
.cindex "AUTH" "configuration"
The authenticators section of the configuration, introduced by
.code
begin authenticators
.endd
-defines mechanisms for the use of the SMTP AUTH command. No authenticators
-are specified in the default configuration file.
+defines mechanisms for the use of the SMTP AUTH command. The default
+configuration file contains two commented-out example authenticators
+which support plaintext username/password authentication using the
+standard PLAIN mechanism and the traditional but non-standard LOGIN
+mechanism, with Exim acting as the server. PLAIN and LOGIN are enough
+to support most MUA software.
+
+The example PLAIN authenticator looks like this:
+.code
+#PLAIN:
+# driver = plaintext
+# server_set_id = $auth2
+# server_prompts = :
+# server_condition = Authentication is not yet configured
+# server_advertise_condition = ${if def:tls_cipher }
+.endd
+And the example LOGIN authenticator looks like this:
+.code
+#LOGIN:
+# driver = plaintext
+# server_set_id = $auth1
+# server_prompts = <| Username: | Password:
+# server_condition = Authentication is not yet configured
+# server_advertise_condition = ${if def:tls_cipher }
+.endd
+
+The &%server_set_id%& option makes Exim remember the authenticated username
+in &$authenticated_id$&, which can be used later in ACLs or routers. The
+&%server_prompts%& option configures the &(plaintext)& authenticator so
+that it implements the details of the specific authentication mechanism,
+i.e. PLAIN or LOGIN. The &%server_advertise_condition%& setting controls
+when Exim offers authentication to clients; in the examples, this is only
+when TLS or SSL has been started, so to enable the authenticators you also
+need to add support for TLS as described in &<<SECTdefconfmain>>&.
+
+The &%server_condition%& setting defines how to verify that the username and
+password are correct. In the examples it just produces an error message.
+To make the authenticators work, you can use a string expansion
+expression like one of the examples in &<<CHAPplaintext>>&.
+
.ecindex IIDconfiwal
list. The effect of each one lasts until the next, or until the end of the
list.
-.new
&*Note*&: This section applies to permanent lookup failures. It does &'not'&
apply to temporary DNS errors. They always cause a defer action (except when
&%dns_again_means_nonexist%& converts them into permanent errors).
-.wen
detected by a regular expression that matches an empty string,
and by a query-style lookup that succeeds when &$sender_address$& is empty.
-.new
Non-empty items in an address list can be straightforward email addresses. For
example:
.code
.endd
The &`\N`& sequences are removed by the expansion, so these items do indeed
start with &"^"& by the time they are being interpreted as address patterns.
-.wen
.next
.cindex "address list" "lookup for complete address"
.cindex "expansion" "inserting from a socket"
.cindex "socket" "use of in expansion"
.cindex "&%readsocket%& expansion item"
-This item inserts data that is read from a Unix domain socket into the expanded
-string. The minimal way of using it uses just two arguments:
+.new
+This item inserts data from a Unix domain or Internet socket into the expanded
+string. The minimal way of using it uses just two arguments, as in these
+examples:
.code
${readsocket{/socket/name}{request string}}
+${readsocket{inet:some.host:1234}{request string}}
.endd
-Exim connects to the socket, writes the request string (unless it is an
-empty string) and reads from the socket until an end-of-file is read. A timeout
-of 5 seconds is applied. Additional, optional arguments extend what can be
-done. Firstly, you can vary the timeout. For example:
+For a Unix domain socket, the first substring must be the path to the socket.
+For an Internet socket, the first substring must contain &`inet:`& followed by
+a host name or IP address, followed by a colon and a port, which can be a
+number or the name of a TCP port in &_/etc/services_&. An IP address may
+optionally be enclosed in square brackets. This is best for IPv6 addresses. For
+example:
+.code
+${readsocket{inet:[::1]:1234}{request string}}
+.endd
+Only a single host name may be given, but if looking it up yields more than
+one IP address, they are each tried in turn until a connection is made. For
+both kinds of socket, Exim makes a connection, writes the request string
+(unless it is an empty string) and reads from the socket until an end-of-file
+is read. A timeout of 5 seconds is applied. Additional, optional arguments
+extend what can be done. Firstly, you can vary the timeout. For example:
+.wen
.code
${readsocket{/socket/name}{request-string}{3s}}
.endd
A fourth argument allows you to change any newlines that are in the data
that is read, in the same way as for &%readfile%& (see above). This example
turns them into spaces:
+.new
.code
-${readsocket{/socket/name}{request-string}{3s}{ }}
+${readsocket{inet:127.0.0.1:3294}{request-string}{3s}{ }}
.endd
+.wen
As with all expansions, the substrings are expanded before the processing
happens. Errors in these sub-expansions cause the expansion to fail. In
addition, the following errors can occur:
${readsocket{/socket/name}{request-string}{3s}{\n}\
{socket failure}}
.endd
-You can test for the existence of the socket by wrapping this expansion in
-&`${if exists`&, but there is a race condition between that test and the
-actual opening of the socket, so it is safer to use the fifth argument if you
-want to be absolutely sure of avoiding an expansion error for a non-existent
-socket.
+.new
+You can test for the existence of a Unix domain socket by wrapping this
+expansion in &`${if exists`&, but there is a race condition between that test
+and the actual opening of the socket, so it is safer to use the fifth argument
+if you want to be absolutely sure of avoiding an expansion error for a
+non-existent Unix domain socket, or a failure to connect to an Internet socket.
+.wen
The &(redirect)& router has an option called &%forbid_filter_readsocket%& which
locks out the use of this expansion item in filter files.
See the description of the general &%substr%& item above for details. The
abbreviation &%s%& can be used when &%substr%& is used as an operator.
-.new
.vitem &*${time_eval:*&<&'string'&>&*}*&
.cindex "&%time_eval%& expansion item"
.cindex "time interval" "decoding"
This item converts an Exim time interval such as &`2d4h5m`& into a number of
seconds.
-.wen
.vitem &*${time_interval:*&<&'string'&>&*}*&
.cindex "&%time_interval%& expansion item"
When, as a result of aliasing or forwarding, a message is directed to a pipe,
this variable holds the pipe command when the transport is running.
-.new
.vitem "&$auth1$& &-- &$auth3$&"
.cindex "&$auth1$&, &$auth2$&, etc"
These variables are used in SMTP authenticators (see chapters
&<<CHAPplaintext>>&&--&<<CHAPspa>>&). Elsewhere, they are empty.
-.wen
.vitem &$authenticated_id$&
.cindex "authentication" "id"
user/password authenticator configuration might preserve the user name for use
in the routers. Note that this is not the same information that is saved in
&$sender_host_authenticated$&. When a message is submitted locally (that is,
-not over a TCP connection), the value of &$authenticated_id$& is the login name
-of the calling process.
+not over a TCP connection) and if the submitter is not a trusted user,
+the value of &$authenticated_id$& is the login name of the calling process.
.vitem &$authenticated_sender$&
.cindex "sender" "authenticated"
.cindex "transport" "filter"
.cindex "&$pipe_addresses$&"
This is not an expansion variable, but is mentioned here because the string
-&"$pipe_addresses"& is handled specially in the command specification for the
+&`$pipe_addresses`& is handled specially in the command specification for the
&(pipe)& transport (chapter &<<CHAPpipetransport>>&) and in transport filters
(described under &%transport_filter%& in chapter &<<CHAPtransportgeneric>>&).
It cannot be used in general expansion strings, and provokes an &"unknown
.cindex "&$reply_address$&"
When a message is being processed, this variable contains the contents of the
&'Reply-To:'& header line if one exists and it is not empty, or otherwise the
-contents of the &'From:'& header line. &new("Apart from the removal of leading
+contents of the &'From:'& header line. Apart from the removal of leading
white space, the value is not processed in any way. In particular, no RFC 2047
-decoding or character code translation takes place.")
+decoding or character code translation takes place.
.vitem &$return_path$&
.cindex "&$return_path$&"
the verified host name or to the host's IP address in square brackets.
.vitem &$sender_helo_name$&
-.cindex "&$sender_hslo_name$&"
+.cindex "&$sender_helo_name$&"
When a message is received from a remote host that has issued a HELO or EHLO
command, the argument of that command is placed in this variable. It is also
set if HELO or EHLO is used when a message is received using SMTP locally via
function.) Of course, this means that the additional functionality of
&[getaddrinfo()]& &-- recognizing scoped addresses &-- is lost.
-.new
.section "Disabling IPv6"
.cindex "IPv6" "disabling"
Sometimes it happens that an Exim binary that was compiled with IPv6 support is
option to globally suppress the lookup of AAAA records for specified domains,
and you can use the &%ignore_target_hosts%& generic router option to ignore
IPv6 addresses in an individual router.
-.wen
.table2
.row &%acl_not_smtp%& "ACL for non-SMTP messages"
.row &%acl_not_smtp_mime%& "ACL for non-SMTP MIME parts"
+.row &%acl_not_smtp_start%& "ACL for start of non-SMTP message"
.row &%acl_smtp_auth%& "ACL for AUTH"
.row &%acl_smtp_connect%& "ACL for connection"
.row &%acl_smtp_data%& "ACL for DATA"
.option acl_not_smtp main string&!! unset
.cindex "&ACL;" "for non-SMTP messages"
.cindex "non-SMTP messages" "ACLs for"
-This option defines the ACL that is run when a non-SMTP message is on the point
-of being accepted. See chapter &<<CHAPACL>>& for further details.
+This option defines the ACL that is run when a non-SMTP message has been
+read and is on the point of being accepted. See chapter &<<CHAPACL>>& for
+further details.
.option acl_not_smtp_mime main string&!! unset
This option defines the ACL that is run for individual MIME parts of non-SMTP
messages. It operates in exactly the same way as &%acl_smtp_mime%& operates for
SMTP messages.
+.option acl_not_smtp_start main string&!! unset
+.cindex "&ACL;" "at start of non-SMTP message"
+.cindex "non-SMTP messages" "ACLs for"
+This option defines the ACL that is run before Exim starts reading a
+non-SMTP message. See chapter &<<CHAPACL>>& for further details.
+
.option acl_smtp_auth main string&!! unset
.cindex "&ACL;" "setting up for SMTP commands"
.cindex "AUTH" "ACL for"
.option bounce_return_body main boolean true
.cindex "bounce message" "including body"
-.new
This option controls whether the body of an incoming message is included in a
bounce message when &%bounce_return_message%& is true. The default setting
causes the entire message, both header and body, to be returned (subject to the
error that is detected during reception, only those header lines preceding the
point at which the error was detected are returned.
.cindex "bounce message" "including original"
-.wen
.option bounce_return_message main boolean true
-.new
If this option is set false, none of the original message is included in
bounce messages generated by Exim. See also &%bounce_return_size_limit%& and
&%bounce_return_body%&.
-.wen
.option bounce_return_size_limit main integer 100K
occur when a delivered message is subsequently sent on to some other recipient.
-.new
.option disable_ipv6 main boolean false
.cindex "IPv6" "disabling"
If this option is set true, even if the Exim binary has IPv6 support, no IPv6
that are listed in &%local_interfaces%&, data for the &%manualroute%& router,
etc. are ignored. If IP literals are enabled, the &(ipliteral)& router declines
to handle IPv6 literal addresses.
-.wen
.option dns_again_means_nonexist main "domain list&!!" unset
.code
dns_again_means_nonexist = *.in-addr.arpa
.endd
-.new
This option applies to all DNS lookups that Exim does. It also applies when the
&[gethostbyname()]& or &[getipnodebyname()]& functions give temporary errors,
since these are most likely to be caused by DNS lookup problems. The
&(dnslookup)& router has some options of its own for controlling what happens
when lookups for MX or SRV records give temporary errors. These more specific
options are applied after this global option.
-.wen
.option dns_check_names_pattern main string "see below"
.cindex "DNS" "pre-check of name syntax"
-.new
When this option is set to a non-empty string, it causes Exim to check domain
names for characters that are not allowed in host names before handing them to
the DNS resolver, because some resolvers give temporary errors for names that
accessed in Exim by using a &%dnsdb%& lookup). If you set
&%allow_utf8_domains%&, you must modify this pattern, or set the option to an
empty string.
-.wen
.option dns_csa_search_limit main integer 5
This option controls the depth of parental searching for CSA SRV records in the
.option dns_ipv4_lookup main "domain list&!!" unset
.cindex "IPv6" "DNS lookup for AAAA records"
.cindex "DNS" "IPv6 lookup for AAAA records"
-.new
When Exim is compiled with IPv6 support and &%disable_ipv6%& is not set, it
looks for IPv6 address records (AAAA records) as well as IPv4 address records
(A records) when trying to find IP addresses for hosts, unless the host's
This is a fudge to help with name servers that give big delays or otherwise do
not work for the AAAA record type. In due course, when the world's name
servers have all been upgraded, there should be no need for this option.
-.wen
.option dns_retrans main time 0s
.option errors_reply_to main string unset
.cindex "bounce message" "&'Reply-to:'& in"
-.new
By default, Exim's bounce and delivery warning messages contain the header line
.display
&`From: Mail Delivery System <Mailer-Daemon@`&&'qualify-domain'&&`>`&
&%quota_warn_message%& option in an &(appendfile)& transport contain its
own &'Reply-To:'& header line, the value of the &%errors_reply_to%& option is
not used.
-.wen
.option exim_group main string "compile-time configured"
If this option is set, queue runs happen in order of message arrival instead of
in an arbitrary order. For this to happen, a complete list of the entire queue
must be set up before the deliveries start. When the queue is all held in a
-single directory (the default),
-
-a single list is created for both the ordered and the non-ordered cases.
-However, if &%split_spool_directory%& is set, a single list is not created when
-&%queue_run_in_order%& is false. In this case, the sub-directories are
-processed one at a time (in a random order), and this avoids setting up one
-huge list for the whole queue. Thus, setting &%queue_run_in_order%& with
-&%split_spool_directory%& may degrade performance when the queue is large,
-because of the extra work in setting up the single, large list. In most
-situations, &%queue_run_in_order%& should not be set.
+single directory (the default), a single list is created for both the ordered
+and the non-ordered cases. However, if &%split_spool_directory%& is set, a
+single list is not created when &%queue_run_in_order%& is false. In this case,
+the sub-directories are processed one at a time (in a random order), and this
+avoids setting up one huge list for the whole queue. Thus, setting
+&%queue_run_in_order%& with &%split_spool_directory%& may degrade performance
+when the queue is large, because of the extra work in setting up the single,
+large list. In most situations, &%queue_run_in_order%& should not be set.
.option retry_interval_max main time 24h
.cindex "retry" "limit on interval"
.cindex "limit" "on retry interval"
-.new
Chapter &<<CHAPretry>>& describes Exim's mechanisms for controlling the
intervals between delivery attempts for messages that cannot be delivered
straight away. This option sets an overall limit to the length of time between
retries. It cannot be set greater than 24 hours; any attempt to do so forces
the default value.
-.wen
.option return_path_remove main boolean true
RFC 1413 identification calls are made to any client host which matches an item
in the list.
-.new
.option rfc1413_query_timeout main time 5s
-.wen
.cindex "RFC 1413" "query timeout"
.cindex "timeout" "for RFC 1413 call"
This sets the timeout on RFC 1413 identification calls. If it is set to zero,
.option tls_privatekey main string&!! unset
.cindex "TLS" "server private key; location of"
-.new
The value of this option is expanded, and must then be the absolute path to a
file which contains the server's private key. If this option is unset, or if
the expansion is forced to fail, or the result is an empty string, the private
key is assumed to be in the same file as the server's certificates. See chapter
&<<CHAPTLS>>& for further details.
-.wen
.option tls_remember_esmtp main boolean false
While the router is running, &%router_home_directory%& overrides the value of
&$home$& that came from &%check_local_user%&.
-.new
When a router accepts an address and assigns it to a local transport (including
the cases when a &(redirect)& router generates a pipe, file, or autoreply
delivery), the home directory setting for the transport is taken from the first
of these values that is set:
-.wen
.ilist
The &%home_directory%& option on the transport;
.code
root@[192.168.1.1]
.endd
-.new
by setting up delivery to the host with that IP address. IPv4 domain literals
consist of an IPv4 address enclosed in square brackets. IPv6 domain literals
are similar, but the address is preceded by &`ipv6:`&. For example:
.endd
Exim allows &`ipv4:`& before IPv4 addresses, for consistency, and on the
grounds that sooner or later somebody will try it.
-.wen
.cindex "&%self%& option" "in &(ipliteral)& router"
If the IP address matches something in &%ignore_target_hosts%&, the router
.option command_group queryprogram string unset
.cindex "gid (group id)" "in &(queryprogram)& router"
-.new
This option specifies a gid to be set when running the command while routing an
address for deliver. It must be set if &%command_user%& specifies a numerical
uid. If it begins with a digit, it is interpreted as the numerical value of the
gid. Otherwise it is looked up using &[getgrnam()]&.
-.wen
.option command_user queryprogram string unset
.cindex "uid (user id)" "for &(queryprogram)&"
-.new
This option must be set. It specifies the uid which is set when running the
command while routing an address for delivery. If the value begins with a digit,
it is interpreted as the numerical value of the uid. Otherwise, it is looked up
is called from a non-root process, Exim cannot change uid or gid before running
the command. In this circumstance the command runs under the current uid and
gid.
-.wen
.option current_directory queryprogram string /
.ilist
When Exim is receiving an incoming SMTP message from a remote host, it is
running under the Exim uid, not as root.
-No additional groups are set up, even if the Exim uid is a member of other
-groups (that is, the &[initgroups()]& function is not run).
Exim is unable to change uid to read the file as the user, and it may not be
able to read it as the Exim user. So in practice the router may not be able to
operate.
.option qualify_domain redirect string&!! unset
.cindex "&$qualify_recipient$&"
-.new
If this option is set, and an unqualified address (one without a domain) is
generated, and that address would normally be qualified by the global setting
in &%qualify_recipient%&, it is instead qualified with the domain specified by
but for traditional &_.forward_& files, it applies only to addresses that are
not preceded by a backslash. Sieve filters cannot generate unqualified
addresses.
-.wen
.option qualify_preserve_domain redirect boolean false
.cindex "domain" "in redirection; preserving"
.cindex "preserving domain in redirection"
.cindex "address redirection" "domain; preserving"
-.new
If this option is set, the router's local &%qualify_domain%& option must not be
set (a configuration error occurs if it is). If an unqualified address (one
without a domain) is generated, it is qualified with the domain of the parent
address (the immediately preceding ancestor) instead of the global
&%qualify_recipient%& value. In the case of a traditional &_.forward_& file,
this applies whether or not the address is preceded by a backslash.
-.wen
.option repeat_use redirect boolean true
.option home_directory transports string&!! unset
.cindex "transport" "home directory for"
.cindex "&$home$&"
-This option specifies a home directory setting for &new("a local") transport,
+This option specifies a home directory setting for a local transport,
overriding any value that may be set by the router. The home directory is
placed in &$home$& while expanding the transport's private options. It is also
used as the current directory if no current directory is set by the
option can be used to support VERP (Variable Envelope Return Paths) &-- see
section &<<SECTverp>>&.
-.new
&*Note*&: If a delivery error is detected locally, including the case when a
remote server rejects a message at SMTP time, the bounce message is not sent to
the value of this option. It is sent to the previously set errors address.
This defaults to the incoming sender address, but can be changed by setting
&%errors_to%& in a router.
-.wen
$host $host_address $sender_address $pipe_addresses
.endd
-.new
Two problems arise if you want to use more complicated expansion items to
generate transport filter commands, both of which due to the fact that the
command is split up &'before'& expansion.
{$value}{/bin/cat}}
.endd
.endlist
-.wen
The filter process is run under the same uid and gid as the normal delivery.
For remote deliveries this is the Exim uid/gid by default. The command should
acceptable.
.endlist
-The three local transports (&(appendfile)&, &(lmtp)&, and &(pipe)&) all have
-the same options for controlling multiple (&"batched"&) deliveries, namely
-&%batch_max%& and &%batch_id%&. To save repeating the information for each
-transport, these options are described here.
+.new
+These three local transports all have the same options for controlling multiple
+(&"batched"&) deliveries, namely &%batch_max%& and &%batch_id%&. To save
+repeating the information for each transport, these options are described here.
The &%batch_max%& option specifies the maximum number of addresses that can be
-delivered together in a single run of the transport. Its default value is one.
-When more than one address is routed to a transport that has a &%batch_max%&
-value greater than one, the addresses are delivered in a batch (that is, in a
-single run of the transport), subject to certain conditions:
+delivered together in a single run of the transport. Its default value is one
+(no batching). When more than one address is routed to a transport that has a
+&%batch_max%& value greater than one, the addresses are delivered in a batch
+(that is, in a single run of the transport with multiple recipients), subject
+to certain conditions:
+.wen
.ilist
.cindex "&$local_part$&"
.cindex "customizing" "batching condition"
If &%batch_id%& is set, it is expanded for each address, and only those
addresses with the same expanded value are batched. This allows you to specify
-customized batching conditions.
-Failure of the expansion for any reason, including forced failure, disables
-batching, but it does not stop the delivery from taking place.
+customized batching conditions. Failure of the expansion for any reason,
+including forced failure, disables batching, but it does not stop the delivery
+from taking place.
.next
Batched addresses must also have the same errors address (where to send
delivery errors), the same header additions and removals, the same user and
be the same.
.endlist
-.cindex "&'Envelope-to:'& header line"
-If the generic &%envelope_to_add%& option is set for the transport, the
-&'Envelope-to:'& header that is added to the message contains all the addresses
-that are batched together.
-
-The &(appendfile)& and &(pipe)& transports have an option called &%use_bsmtp%&,
-which causes them to deliver the message in &"batched SMTP"& format, with the
-envelope represented as SMTP commands. The &%check_string%& and
-&%escape_string%& options are forced to the values
+.new
+In the case of the &(appendfile)& and &(pipe)& transports, batching applies
+both when the file or pipe command is specified in the transport, and when it
+is specified by a &(redirect)& router, but all the batched addresses must of
+course be routed to the same file or pipe command. These two transports have an
+option called &%use_bsmtp%&, which causes them to deliver the message in
+&"batched SMTP"& format, with the envelope represented as SMTP commands. The
+&%check_string%& and &%escape_string%& options are forced to the values
.code
check_string = "."
escape_string = ".."
given in section &<<SECTbatchSMTP>>&. The &(lmtp)& transport does not have a
&%use_bsmtp%& option, because it always delivers using the SMTP protocol.
+.cindex "&'Envelope-to:'& header line"
+If the generic &%envelope_to_add%& option is set for a batching transport, the
+&'Envelope-to:'& header that is added to the message contains all the addresses
+that are being processed together. If you are using a batching &(appendfile)&
+transport without &%use_bsmtp%&, the only way to preserve the recipient
+addresses is to set the &%envelope_to_add%& option.
+
.cindex "&(pipe)& transport" "with multiple addresses"
.cindex "&$pipe_addresses$&"
-If you are not using BSMTP, but are using a &(pipe)& transport, you can include
-&$pipe_addresses$& as part of the command. This is not a true variable; it is
-a bit of magic that causes each of the recipient addresses to be inserted into
-the command as a separate argument. This provides a way of accessing all the
-addresses that are being delivered in the batch.
+If you are using a &(pipe)& transport without BSMTP, and setting the
+transport's &%command%& option, you can include &$pipe_addresses$& as part of
+the command. This is not a true variable; it is a bit of magic that causes each
+of the recipient addresses to be inserted into the command as a separate
+argument. This provides a way of accessing all the addresses that are being
+delivered in the batch. &*Note:*& This is not possible for pipe commands that
+are specififed by a &(redirect)& router.
+.wen
-If you are using a batching &(appendfile)& transport without &%use_bsmtp%&, the
-only way to preserve the recipient addresses is to set the &%envelope_to_add%&
-option. This causes an &'Envelope-to:'& header line to be added to the message,
-containing all the recipients.
.option lockfile_mode appendfile "octal integer" 0600
+.new
This specifies the mode of the created lock file, when a lock file is being
-used (see &%use_lockfile%&).
+used (see &%use_lockfile%& and &%use_mbx_lock%&).
+.wen
.option lockfile_timeout appendfile time 30m
.option maildir_quota_directory_regex appendfile string "See below"
.cindex "maildir format" "quota; directories included in"
.cindex "quota" "maildir; directories included in"
+.new
This option is relevant only when &%maildir_use_size_file%& is set. It defines
-a regular expression for specifying directories that should be included in the
-quota calculation. The default value is
+a regular expression for specifying directories, relative to the quota
+directory (see &%quota_directory%&), that should be included in the quota
+calculation. The default value is:
+.wen
.code
maildir_quota_directory_regex = ^(?:cur|new|\..*)$
.endd
-which includes the &_cur_& and &_new_& directories, and any maildir++ folders
+This includes the &_cur_& and &_new_& directories, and any maildir++ folders
(directories whose names begin with a dot). If you want to exclude the
&_Trash_&
folder from the count (as some sites do), you need to change this setting to
.code
maildir_quota_directory_regex = ^(?:cur|new|\.(?!Trash).*)$
.endd
+.new
This uses a negative lookahead in the regular expression to exclude the
-directory whose name is &_.Trash_&.
+directory whose name is &_.Trash_&. When a directory is excluded from quota
+calculations, quota processing is bypassed for any messages that are delivered
+directly into that directory.
+.wen
.option maildir_retries appendfile integer 10
.option maildir_use_size_file appendfile boolean false
.cindex "maildir format" "&_maildirsize_& file"
+.new
Setting this option true enables support for &_maildirsize_& files. Exim
creates a &_maildirsize_& file in a maildir if one does not exist, taking the
quota from the &%quota%& option of the transport. If &%quota%& is unset, the
-value is zero. See section &<<SECTmaildirdelivery>>& below for further details.
+value is zero. See &%maildir_quota_directory_regex%& above and section
+&<<SECTmaildirdelivery>>& below for further details.
+.wen
+
+.new
+.option maildirfolder_create_regex appendfile string unset
+.cindex "maildir format" "&_maildirfolder_& file"
+.cindex "&_maildirfolder_&, creating"
+The value of this option is a regular expression. If it is unset, it has no
+effect. Otherwise, before a maildir delivery takes place place, the pattern is
+matched against the name of the maildir directory, that is, the directory
+containing the &_new_& and &_tmp_& subdirectories that will be used for the
+delivery. If there is a match, Exim checks for the existence of a file called
+&_maildirfolder_& in the directory, and creates it if it does not exist.
+See section &<<SECTmaildirdelivery>>& for more details.
+.wen
.option mailstore_format appendfile boolean false
.option quota_filecount appendfile string&!! 0
-.new
This option applies when the &%directory%& option is set. It limits the total
number of files in the directory (compare the inode limit in system quotas). It
can only be used if &%quota%& is also set. The value is expanded; an expansion
failure causes delivery to be deferred. A value of zero is interpreted as
&"no quota"&.
-.wen
.option quota_is_inclusive appendfile boolean true
If &%quota%& is not set, a setting of &%quota_warn_threshold%& that ends with a
percent sign is ignored.
-.new
The warning message itself is specified by the &%quota_warn_message%& option,
and it must start with a &'To:'& header line containing the recipient(s) of the
warning message. These do not necessarily have to include the recipient(s) of
.oindex &%errors_reply_to%&
If you supply a &'Reply-To:'& line, it overrides the global &%errors_reply_to%&
option.
-.wen
The &%quota%& option does not have to be set in order to use this option; they
are independent of one another except when the threshold is specified as a
.code
/tmp/.<device-number>.<inode-number>
.endd
+.new
using the device and inode numbers of the open mailbox file, in accordance with
-the MBX locking rules.
+the MBX locking rules. This file is created with a mode that is specified by
+the &%lockfile_mode%& option.
+.wen
If Exim fails to lock the file, there are two possible courses of action,
depending on the value of the locking timeout. This is obtained from
.section "Maildir delivery" "SECTmaildirdelivery"
.cindex "maildir format" "description of"
+.new
If the &%maildir_format%& option is true, Exim delivers each message by writing
it to a file whose name is &_tmp/<stime>.H<mtime>P<pid>.<host>_& in the
-given directory. If the delivery is successful, the file is renamed into the
+directory that is defined by the &%directory%& option (the &"delivery
+directory"&). If the delivery is successful, the file is renamed into the
&_new_& subdirectory.
+.wen
In the file name, <&'stime'&> is the current time of day in seconds, and
<&'mtime'&> is the microsecond fraction of the time. After a maildir delivery,
opening it. If any response other than ENOENT (does not exist) is given,
Exim waits 2 seconds and tries again, up to &%maildir_retries%& times.
+.new
+Before Exim carries out a maildir delivery, it ensures that subdirectories
+called &_new_&, &_cur_&, and &_tmp_& exist in the delivery directory. If they
+do not exist, Exim tries to create them and any superior directories in their
+path, subject to the &%create_directory%& and &%create_file%& options. If the
+&%maildirfolder_create_regex%& option is set, and the regular expression it
+contains matches the delivery directory, Exim also ensures that a file called
+&_maildirfolder_& exists in the delivery directory. If a missing directory or
+&_maildirfolder_& file cannot be created, delivery is deferred.
+
+These features make it possible to use Exim to create all the necessary files
+and directories in a maildir mailbox, including subdirectories for maildir++
+folders. Consider this example:
+.code
+maildir_format = true
+directory = /var/mail/$local_part\
+ ${if eq{$local_part_suffix}{}{}\
+ {/.${substr_1:$local_part_suffix}}}
+maildirfolder_create_regex = /\.[^/]+$
+.endd
+If &$local_part_suffix$& is empty (there was no suffix for the local part),
+delivery is into a toplevel maildir with a name like &_/var/mail/pimbo_& (for
+the user called &'pimbo'&). The pattern in &%maildirfolder_create_regex%& does
+not match this name, so Exim will not look for or create
+&_/var/mail/pimbo/maildirfolder_&, though it will create
+&_/var/mail/pimbo/{cur,new,tmp}_& if necessary.
+
+However, if &$local_part_suffix$& contains &`-eximusers`& (for example),
+delivery is into the maildir++ folder &_/var/mail/pimbo/.eximusers_&, which
+does match &%maildirfolder_create_regex%&. In this case, Exim will create
+&_/var/mail/pimbo/.eximusers/maildirfolder_& as well as the three maildir
+directories &_/var/mail/pimbo/.eximusers/{cur,new,tmp}_&.
+
+&*Warning:*& Take care when setting &%maildirfolder_create_regex%& that it does
+not inadvertently match the toplevel maildir directory, because a
+&_maildirfolder_& file at top level would completely break quota calculations.
+.wen
+
.cindex "quota" "in maildir delivery"
.cindex "maildir++"
If Exim is required to check a &%quota%& setting before a maildir delivery, and
.cindex "maildir format" "&_maildirsize_& file"
If &%maildir_use_size_file%& is true, Exim implements the maildir++ rules for
storing quota and message size information in a file called &_maildirsize_&
-within the maildir directory. If this file does not exist, Exim creates it,
-setting the quota from the &%quota%& option of the transport. If the maildir
-directory itself does not exist, it is created before any attempt to write a
-&_maildirsize_& file.
+within the toplevel maildir directory. If this file does not exist, Exim
+creates it, setting the quota from the &%quota%& option of the transport. If
+the maildir directory itself does not exist, it is created before any attempt
+to write a &_maildirsize_& file.
The &_maildirsize_& file is used to hold information about the sizes of
messages in the maildir, thus speeding up quota calculations. The quota value
If the &%quota%& option in the transport is unset or zero, the &_maildirsize_&
file is maintained (with a zero quota setting), but no quota is imposed.
+.new
A regular expression is available for controlling which directories in the
-maildir participate in quota calculations. See the description of the
-&%maildir_quota_directory_regex%& option above for details.
-
+maildir participate in quota calculations when a &_maildirsizefile_& is in use.
+See the description of the &%maildir_quota_directory_regex%& option above for
+details.
+.wen
.section "Mailstore delivery"
.chapter "The autoreply transport"
.scindex IIDauttra1 "transports" "&(autoreply)&"
.scindex IIDauttra2 "&(autoreply)& transport"
-.new
The &(autoreply)& transport is not a true transport in that it does not cause
the message to be transmitted. Instead, it generates a new mail message as an
automatic reply to the incoming message. &'References:'& and
&'Auto-Submitted:'& header lines are included. These are constructed according
to the rules in RFCs 2822 and 3834, respectively.
-.wen
If the router that passes the message to this transport does not have the
&%unseen%& option set, the original message (for the current recipient) is not
.option never_mail autoreply "address list&!!" unset
+.new
If any run of the transport creates a message with a recipient that matches any
item in the list, that recipient is quietly discarded. If all recipients are
-discarded, no message is created.
+discarded, no message is created. This applies both when the recipients are
+generated by a filter and when they are specified in the transport.
+.wen
contains the local part of the address (as usual), and the command that is run
is specified by the &%command%& option on the transport.
.next
+.new
.cindex "&$pipe_addresses$&"
-If the &%batch_max%& option is set greater than 1 (the default), the transport
-can be called upon to handle more than one address in a single run. In this
-case, &$local_part$& is not set (because it is not unique). However, the
-pseudo-variable &$pipe_addresses$& (described in section
-&<<SECThowcommandrun>>& below) contains all the addresses that are being
-handled.
+If the &%batch_max%& option is set greater than 1 (the default is 1), the
+transport can handle more than one address in a single run. In this case, when
+more than one address is routed to the transport, &$local_part$& is not set
+(because it is not unique). However, the pseudo-variable &$pipe_addresses$&
+(described in section &<<SECThowcommandrun>>& below) contains all the addresses
+that are routed to the transport.
.next
.cindex "&$address_pipe$&"
A router redirects an address directly to a pipe command (for example, from an
-alias or forward file). In this case, &$local_part$& contains the local part
-that was redirected, and &$address_pipe$& contains the text of the pipe
-command itself. The &%command%& option on the transport is ignored.
+alias or forward file). In this case, &$address_pipe$& contains the text of the
+pipe command, and the &%command%& option on the transport is ignored. If only
+one address is being transported (&%batch_max%& is not greater than one, or
+only one address was redirected to this pipe command), &$local_part$& contains
+the local part that was redirected.
+.wen
.endlist
other cases, the uid and gid have to be specified explicitly, either on the
transport or on the router that handles the address. Current and &"home"&
directories are also controllable. See chapter &<<CHAPenvironment>>& for
-details of the local delivery environment.
-
+details of the local delivery environment &new("and chapter &<<CHAPbatching>>&
+for a discussion of local delivery batching.")
.section "Concurrent delivery"
.code
command = /some/path "${if eq{$local_part}{postmaster}{xx}{yy}}"
.endd
-.new
to ensure that it is all in one argument. The expansion is done in this way,
argument by argument, so that the number of arguments cannot be changed as a
result of expansion, and quotes or backslashes in inserted variables do not
.code
command = /bin/sh -c ${lookup{$local_part}lsearch{/some/file}}
.endd
-.wen
.cindex "transport" "filter"
.cindex "filter" "transport filter"
you can do so by setting the &%message_prefix%& option. See section
&<<SECTbatchSMTP>>& for details of batch SMTP.
-.new
.option use_classresources pipe boolean false
.cindex "class resources (BSD)"
This option is available only when Exim is running on FreeBSD, NetBSD, or
resource limits when a &(pipe)& transport is run to perform a delivery. The
limits for the uid under which the pipe is to run are obtained from the login
class database.
-.wen
.option use_crlf pipe boolean false
.option authenticated_sender smtp string&!! unset
.cindex "Cyrus"
-.new
When Exim has authenticated as a client, or if &%authenticated_sender_force%&
is true, this option sets a value for the AUTH= item on outgoing MAIL commands,
overriding any existing authenticated sender value. If the string expansion is
&%authenticated_sender%& still happens (and can cause the delivery to be
deferred if it fails), but no AUTH= item is added to MAIL commands
unless &%authenticated_sender_force%& is true.
-.wen
This option allows you to use the &(smtp)& transport in LMTP mode to
deliver mail to Cyrus IMAP and provide the proper local part as the
value.
-.new
.option authenticated_sender_force smtp boolean false
If this option is set true, the &%authenticated_sender%& option's value
is used for the AUTH= item on outgoing MAIL commands, even if Exim has not
authenticated as a client.
-.wen
.option command_timeout smtp time 5m
.option helo_data smtp string&!! &`$primary_hostname`&
.cindex "HELO argument" "setting"
.cindex "EHLO argument" "setting"
-The value of this option is expanded, and used as the argument for the EHLO or
-HELO command that starts the outgoing SMTP session. The variables &$host$& and
-&$host_address$& are set to the identity of the remote host, and can be used to
-generate different values for different servers.
+.cindex "LHLO argument" "setting"
+.new
+The value of this option is expanded, and used as the argument for the EHLO,
+HELO, or LHLO command that starts the outgoing SMTP or LMTP session. The
+variables &$host$& and &$host_address$& are set to the identity of the remote
+host, and can be used to generate different values for different servers.
+.wen
.option hosts smtp "string list&!!" unset
Hosts are associated with an address by a router such as &(dnslookup)&, which
.cindex "TLS client private key" "location of"
.cindex "&$host$&"
.cindex "&$host_address$&"
-.new
The value of this option must be the absolute path to a file which contains the
client's private key. This is used when sending a message over an encrypted
connection using a client certificate. The values of &$host$& and
expansion. If this option is unset, or the expansion is forced to fail, or the
result is an empty string, the private key is assumed to be in the same file as
the certificate. See chapter &<<CHAPTLS>>& for details of TLS.
-.wen
.option tls_require_ciphers smtp string&!! unset
as they were before (that is, they contain the unrewritten &-- except for
SMTP-time rewriting &-- address).
-.new
As soon as a message's header lines have been received, all the envelope
recipient addresses are permanently rewritten, and rewriting is also applied to
the addresses in the header lines (if configured). This happens before adding
any header lines that were specified in MAIL or RCPT ACLs, and
.cindex "&[local_scan()]& function" "address rewriting; timing of"
before the DATA ACL and &[local_scan()]& functions are run.
-.wen
When an address is being routed, either for delivery or for verification,
rewriting is applied immediately to child addresses that are generated by
redirection, unless &%no_rewrite%& is set on the router.
-.new
.cindex "envelope sender" "rewriting at transport time"
.cindex "rewriting" "at transport time"
.cindex "header lines" "rewriting at transport time"
The outgoing envelope sender can be rewritten by means of the &%return_path%&
transport option. However, it is not possible to rewrite envelope recipients at
transport time.
-.wen
&%retry_use_local_part%& is set for the transport (it defaults true for all
local transports).
-.new
However, when Exim is looking for a retry rule after a remote delivery attempt
suffers an address error (a 4&'xx'& SMTP response for a recipient address), the
whole address is always used as the key when searching the retry rules. The
rule that is found is used to create a retry time for the failing address.
-.wen
.section "Choosing which retry rule to use for host and message errors"
Authentication failed when trying to send to a host in the
&%hosts_require_auth%& list in an &(smtp)& transport.
-.new
.vitem &%data_4xx%&
A 4&'xx'& error was received for an outgoing DATA command, either immediately
after the command, or after sending the message's data.
.endd
These errors apply to both outgoing SMTP (the &(smtp)& transport) and outgoing
LMTP (either the &(lmtp)& transport, or the &(smtp)& transport in LMTP mode).
-.wen
.vlist
-.new
.vitem &%lost_connection%&
A server unexpectedly closed the SMTP connection. There may, of course,
legitimate reasons for this (host died, network died), but if it repeats a lot
for the same host, it indicates something odd.
-.wen
.vitem &%refused_MX%&
A connection to a host obtained from an MX record was refused.
.vitem &%timeout%&
There was a timeout while connecting or during an SMTP session.
-.new
.vitem &%tls_required%&
The server was required to use TLS (it matched &%hosts_require_tls%& in the
&(smtp)& transport), but either did not offer TLS, or it responded with 4&'xx'&
to STARTTLS, or there was a problem setting up the TLS connection.
-.wen
.vitem &%quota%&
A mailbox quota was exceeded in a local delivery by the &(appendfile)&
.code
* rcpt_4xx senders=: F,1h,30m
.endd
-.new
matches recipient 4&'xx'& errors for bounce messages sent to any address at any
host. If the address list contains white space, it must be enclosed in quotes.
For example:
.code
a.domain rcpt_452 senders="xb.dom : yc.dom" G,8h,10m,1.5
.endd
-.wen
&*Warning*&: This facility can be unhelpful if it is used for host errors
(which do not depend on the recipient). The reason is that the sender is used
only to match the retry rule. Once the rule has been found for a host error,
.cindex "limit" "retry interval"
.cindex "retry interval" "maximum"
.cindex "&%retry_interval_max%&"
-&%retry_interval_max%& limits the maximum interval between retries. &new("It
-cannot be set greater than &`24h`&, which is its default value.")
+&%retry_interval_max%& limits the maximum interval between retries. It
+cannot be set greater than &`24h`&, which is its default value.
A single remote domain may have a number of hosts associated with it, and each
host may have more than one IP address. Retry algorithms are selected on the
deliver to permanently failing IP addresses than when &%delay_after_cutoff%& is
true.
-.new
.section "Deliveries that work intermittently"
.cindex "retry" "intermittently working deliveries"
+.new
Some additional logic is needed to cope with cases where a host is
intermittently available, or when a message has some attribute that prevents
its delivery when others to the same address get through. In this situation,
because some messages are successfully delivered, the &"retry clock"& for the
-host or address keeps getting restarted, and so a message could remain on the
-queue for ever because the cutoff time is never reached.
-
-Two exceptional actions are applied to prevent this happening. Firstly, if a
-message's arrival time is earlier than the &"first failed"& time for a host or
-address, the earlier time is used when scanning the retry rules.
-
-Secondly, if a message has been on the queue for longer than the cutoff time of
-any applicable retry rule for a given address, a delivery is attempted for that
-address, even if it is not yet time, and if this delivery fails, the address is
-timed out. A new retry time is not computed in this case, so that other
-messages for the same address are considered immediately.
-
-These two actions are probably equivalent; the fact that they both exist is a
-a historical accident. The second was implemented first, and was left in place
-when the first was added on the grounds that this was harmless, whereas
-removing it might have broken something in this rather tricky area.
+host or address keeps getting reset by the successful deliveries, and so
+failing messages remain on the queue for ever because the cutoff time is never
+reached.
+
+Two exceptional actions are applied to prevent this happening. The first
+applies to errors that are related to a message rather than a remote host.
+Section &<<SECToutSMTPerr>>& has a discussion of the different kinds of error;
+examples of message-related errors are 4&'xx'& responses to MAIL or DATA
+commands, and quota failures. For this type of error, if a message's arrival
+time is earlier than the &"first failed"& time for the error, the earlier time
+is used when scanning the retry rules to decide when to try next and when to
+time out the address.
+
+The exceptional second action applies in all cases. If a message has been on
+the queue for longer than the cutoff time of any applicable retry rule for a
+given address, a delivery is attempted for that address, even if it is not yet
+time, and if this delivery fails, the address is timed out. A new retry time is
+not computed in this case, so that other messages for the same address are
+considered immediately.
+.wen
.ecindex IIDretconf1
.ecindex IIDregconf2
-.wen
.chapter "The plaintext authenticator" "CHAPplaintext"
.scindex IIDplaiauth1 "&(plaintext)& authenticator"
.scindex IIDplaiauth2 "authenticators" "&(plaintext)&"
-.new
The &(plaintext)& authenticator can be configured to support the PLAIN and
LOGIN authentication mechanisms, both of which transfer authentication data as
plain (unencrypted) text (though base64 encoded). The use of plain text is a
(see chapter &<<CHAPTLS>>&) if you use the PLAIN or LOGIN mechanisms. If you do
use unencrypted plain text, you should not use the same passwords for SMTP
connections as you do for login accounts.
-.wen
.section "Using plaintext in a server"
.cindex "options" "&(plaintext)& authenticator (server)"
"in &(plaintext)& authenticator"
.cindex "&$auth1$&, &$auth2$&, etc"
.cindex "base64 encoding" "in &(plaintext)& authenticator"
-.new
The data sent by the client with the AUTH command, or in response to
subsequent prompts, is base64 encoded, and so may contain any byte values
when decoded. If any data is supplied with the command, it is treated as a
the expansion variables &$1$&, &$2$&, and &$3$&. However, the use of these
variables for this purpose is now deprecated, as it can lead to confusion in
string expansions that also use them for other things.
-.wen
If there are more strings in &%server_prompts%& than the number of strings
supplied with the AUTH command, the remaining prompts are used to obtain more
The second and third strings are a user name and a corresponding password.
Using a single fixed user name and password as an example, this could be
configured as follows:
-.new
.code
fixed_plain:
driver = plaintext
realistic, though for a small organization with only a handful of
authenticating clients it could make sense.
-.new
A more sophisticated instance of this authenticator could use the user name in
&$auth2$& to look up a password in a file or database, and maybe do an encrypted
comparison (see &%crypteq%& in chapter &<<CHAPexpand>>&). Here is a example of
server_condition = ${lookup{$auth2}dbm{/etc/authpwd}\
{${if eq{$value}{$auth3}{yes}{no}}}{no}}
.endd
-.wen
In this case, if the lookup succeeds, the result is checked; if the lookup
fails, authentication fails. If &%crypteq%& is being used instead of &%eq%&,
the first example is in fact safe, because &%crypteq%& always fails if its
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
plaintext authenticator can be configured to support this as in this example:
-.new
.code
fixed_login:
driver = plaintext
{yes}{no}}
server_set_id = $auth1
.endd
-.wen
Because of the way plaintext operates, this authenticator accepts data supplied
with the AUTH command (in contravention of the specification of LOGIN), but
if the client does not supply it (as is the case for LOGIN clients), the prompt
&"Password:"&. Here is an example of a LOGIN authenticator that uses those
strings. It uses the &%ldapauth%& expansion condition to check the user
name and password by binding to an LDAP server:
-.new
.code
login:
driver = plaintext
ldap://ldap.example.org/}{yes}{no}}
server_set_id = uid=$auth1,ou=people,o=example.org
.endd
-.wen
Note the use of the &%quote_ldap_dn%& operator to correctly quote the DN for
authentication. However, the basic &%quote%& operator, rather than any of the
LDAP quoting operators, is the correct one to use for the password, because
.cindex "options" "&(plaintext)& authenticator (client)"
The &(plaintext)& authenticator has two client options:
-.new
.option client_ignore_invalid_base64 plaintext boolean false
If the client receives a server prompt that is not a valid base64 string,
authentication is abandoned by default. However, if this option is set true,
the error in the challenge is ignored and the client sends the response as
usual.
-.wen
.option client_send plaintext string&!! unset
-.new
The string is a colon-separated list of authentication data strings. Each
string is independently expanded before being sent to the server. The first
string is sent with the AUTH command; any more strings are sent in response
so on. If an invalid base64 string is received when
&%client_ignore_invalid_base64%& is set, an empty string is put in the
&$auth$&<&'n'&> variable.
-.wen
&*Note*&: You cannot use expansion to create multiple strings, because
splitting takes priority and happens first.
.option server_secret cram_md5 string&!! unset
.cindex "numerical variables (&$1$& &$2$& etc)" "in &(cram_md5)& authenticator"
When the server receives the client's response, the user name is placed in
-the expansion variable &new("&$auth1$&"), and &%server_secret%& is expanded to
+the expansion variable &$auth1$&, and &%server_secret%& is expanded to
obtain the password for that user. The server then computes the CRAM-MD5 digest
that the client should have sent, and checks that it received the correct
string. If the expansion of &%server_secret%& is forced to fail, authentication
fails. If the expansion fails for some other reason, a temporary error code is
returned to the client.
-.new
For compatibility with previous releases of Exim, the user name is also placed
in &$1$&. However, the use of this variables for this purpose is now
deprecated, as it can lead to confusion in string expansions that also use
numeric variables for other things.
-.wen
For example, the following authenticator checks that the user name given by the
client is &"ph10"&, and if so, uses &"secret"& as the password. For any other
user name, authentication fails.
-.new
.code
fixed_cram:
driver = cram_md5
server_secret = ${if eq{$auth1}{ph10}{secret}fail}
server_set_id = $auth1
.endd
-.wen
.cindex "&$authenticated_id$&"
If authentication succeeds, the setting of &%server_set_id%& preserves the user
name in &$authenticated_id$&. A more tyical configuration might look up the
secret string in a file, using the user name as the key. For example:
-.new
.code
lookup_cram:
driver = cram_md5
server_secret = ${lookup{$auth1}lsearch{/etc/authpwd}{$value}fail}
server_set_id = $auth1
.endd
-.wen
Note that this expansion explicitly forces failure if the lookup fails
because &$1$& contains an unknown user name.
.section "Using cyrus_sasl as a server"
-.new
The &(cyrus_sasl)& authenticator has four private options. It puts the username
(on a successful authentication) into &$auth1$&. For compatibility with
previous releases of Exim, the username is also placed in &$1$&. However, the
use of this variable for this purpose is now deprecated, as it can lead to
confusion in string expansions that also use numeric variables for other
things.
-.wen
.option server_hostname cyrus_sasl string&!! &`$primary_hostname`&
This option selects the authentication mechanism this driver should
use. It allows you to use a different underlying mechanism from the
advertised name. For example:
-.new
.code
sasl:
driver = cyrus_sasl
server_mech = CRAM-MD5
server_set_id = $auth1
.endd
-.wen
.option server_realm cyrus_sasl string unset
This specifies the SASL realm that the server claims to be in.
private options. All you need to do is to specify an appropriate mechanism as
the public name. Thus, if you have a SASL library that supports CRAM-MD5 and
PLAIN, you could have two authenticators as follows:
-.new
.code
sasl_cram_md5:
driver = cyrus_sasl
public_name = PLAIN
server_set_id = $auth1
.endd
-.wen
Cyrus SASL does implement the LOGIN authentication method, even though it is
not a standard method. It is disabled by default in the source distribution,
but it is present in many binary distributions.
.option server_password spa string&!! unset
.cindex "numerical variables (&$1$& &$2$& etc)" "in &(spa)& authenticator"
-.new
This option is expanded, and the result must be the cleartext password for the
authenticating user, whose name is at this point in &$auth1$&. For
compatibility with previous releases of Exim, the user name is also placed in
server_password = \
${lookup{$auth1}lsearch{/etc/exim/spa_clearpass}{$value}fail}
.endd
-.wen
If the expansion is forced to fail, authentication fails. Any other expansion
failure causes a temporary error code to be returned.
tls_certificate = /some/file/name
tls_privatekey = /some/file/name
.endd
-.new
These options are, in fact, expanded strings, so you can make them depend on
the identity of the client that is connected if you wish. The first file
contains the server's X509 certificate, and the second contains the private key
is assumed to be the case. The certificate file may also contain intermediate
certificates that need to be sent to the client to enable it to authenticate
the server's certificate.
-.wen
If you do not understand about certificates and keys, please try to find a
source of this background information, which is not Exim-specific. (There are a
few comments below in section &<<SECTcerandall>>&.)
-.new
&*Note*&: These options do not apply when Exim is operating as a client &--
they apply only in the case of a server. If you need to use a certificate in an
Exim client, you must set the options of the same names in an &(smtp)&
With just these options, an Exim server will be able to use TLS. It does not
require the client to have a certificate (but see below for how to insist on
this). There is one other option that may be needed in other situations. If
-.wen
.code
tls_dhparam = /some/file/name
.endd
.cindex "VRFY" "ACL for"
.cindex "SMTP connection" "ACL for"
.cindex "non-smtp message" "ACL for"
+.cindex "MIME parts" "ACL for"
.table2 140pt
.row &~&%acl_not_smtp%& "ACL for non-SMTP messages"
+.row &~&%acl_not_smtp_mime%& "ACL for non-SMTP MIME parts"
+.row &~&%acl_not_smtp_start%& "ACL at start of non-SMTP message"
.row &~&%acl_smtp_auth%& "ACL for AUTH"
.row &~&%acl_smtp_connect%& "ACL for start of SMTP connection"
.row &~&%acl_smtp_data%& "ACL after DATA is complete"
.section "Finding an ACL to use"
.cindex "&ACL;" "finding which to use"
-The value of an &%acl_smtp_%&&'xxx'& option is expanded before use, so you can
-use different ACLs in different circumstances. The resulting string does not
-have to be the name of an ACL in the configuration file; there are other
-possibilities. Having expanded the string, Exim searches for an ACL as follows:
+The value of an &%acl_smtp_%&&'xxx'& option is expanded before use, so
+you can use different ACLs in different circumstances. For example,
+.code
+acl_smtp_rcpt = ${if ={25}{$interface_port} \
+ {acl_check_rcpt} {acl_check_rcpt_submit} }
+.endd
+In the default configuration file there are some example settings for
+providing an RFC 4409 message submission service on port 587 and a
+non-standard &"smtps"& service on port 465. You can use a string
+expansion like this to choose an ACL for MUAs on these ports which is
+more appropriate for this purpose than the default ACL on port 25.
+
+The expanded string does not have to be the name of an ACL in the
+configuration file; there are other possibilities. Having expanded the
+string, Exim searches for an ACL as follows:
.ilist
If the string begins with a slash, Exim uses it as a file name, and reads its
of these variables:
.ilist
-The values of &$acl_c0$& to &new(&$acl_c19$&) persist throughout an SMTP
+The values of &$acl_c0$& to &$acl_c19$& persist throughout an SMTP
connection. They are never reset. Thus, a value that is set while receiving one
message is still available when receiving the next message on the same SMTP
connection.
.next
-The values of &$acl_m0$& to &new(&$acl_m19$&) persist only while a message is
+The values of &$acl_m0$& to &$acl_m19$& persist only while a message is
being received. They are reset afterwards. They are also reset by MAIL, RSET,
EHLO, HELO, and after starting up a TLS session.
.endlist
The ACL modifiers are as follows:
.vlist
-.new
.vitem &*add_header*&&~=&~<&'text'&>
This modifier specifies one of more header lines that are to be added to an
incoming message, assuming, of course, that the message is ultimately
accepted. For details, see section &<<SECTaddheadacl>>&.
-.wen
.vitem &*control*&&~=&~<&'text'&>
.cindex "&%control%&" "ACL modifier"
routers to be passed back as part of the SMTP response, you should either not
use a &%message%& modifier, or make use of &$acl_verify_message$&.
-.new
For compatibility with previous releases of Exim, a &%message%& modifier that
is used with a &%warn%& verb behaves in a similar way to the &%add_header%&
modifier, but this usage is now deprecated. However, &%message%& acts only when
&%add_header%& acts as soon as it is encountered. If &%message%& is used with
&%warn%& in an ACL that is not concerned with receiving a message, it has no
effect.
-.wen
.vitem &*set*&&~<&'acl_name'&>&~=&~<&'value'&>
.cindex "&%set%&" "ACL modifier"
The &%control%& modifier supports the following settings:
.vlist
-.new
.vitem &*control&~=&~allow_auth_unadvertised*&
This modifier allows a client host to use the SMTP AUTH command even when it
has not been advertised in response to EHLO. Furthermore, because there are
matches an advertised mechanism. When this control is set, the check that a
mechanism has been advertised is bypassed. Any configured mechanism can be used
by the client. This control is permitted only in the connection and HELO ACLs.
-.wen
.vitem &*control&~=&~caseful_local_part*&
current message, not to any subsequent ones that may be received in the same
SMTP connection.
-.new
This modifier can optionally be followed by &`/no_tell`&. If the global option
&%freeze_tell%& is set, it is ignored for the current message (that is, nobody
is told about the freezing), provided all the &*control=freeze*& modifiers that
are obeyed for the current message have the &`/no_tell`& option.
-.wen
.vitem &*control&~=&~no_mbox_unspool*&
-.new
.section "Adding header lines in ACLs" "SECTaddheadacl"
.cindex "header lines" "adding in an ACL"
.cindex "header lines" "position of added lines"
&*Warning*&: This facility currently applies only to header lines that are
added in an ACL. It does NOT work for header lines that are added in a
system filter or in a router or transport.
-.wen
timeout checks succeed. The &$prvscheck_result$& variable contains the result
of the checks (empty for failure, &"1"& for success).
-.new
There are two more issues you must consider when implementing prvs-signing.
Firstly, you need to ensure that prvs-signed addresses are not blocked by your
ACLs. A prvs-signed address contains a slash character, but the default Exim
.endd
This is a conservative rule that blocks local parts that contain slashes. You
should remove the slash in the last line.
-.wen
Secondly, you have to ensure that the routers accept prvs-signed addresses and
deliver them correctly. The easiest way to handle this is to use a &(redirect)&
it always return &"true"& by appending &`:true`& to the username.
.cindex "spam scanning" "returned variables"
-When the &%spam%& condition is run, it sets up the following expansion
-variables:
+.new
+When the &%spam%& condition is run, it sets up a number of expansion
+variables. With the exception of &$spam_score_int$&, these are usable only
+within ACLs; their values are not retained with the message and so cannot be
+used at delivery time.
+.wen
.vlist
.vitem &$spam_score$&
.vitem &$spam_score_int$&
The spam score of the message, multiplied by ten, as an integer value. For
example &"34"& or &"305"&. This is useful for numeric comparisons in
-conditions. This variable is special; it is saved with the message, and written
-to Exim's spool file. This means that it can be used during the whole life of
-the message on your Exim system, in particular, in routers or transports during
-the later delivery phase.
+conditions. This variable is special; its value is saved with the message, and
+written to Exim's spool file. This means that it can be used during the whole
+life of the message on your Exim system, in particular, in routers or
+transports during the later delivery phase.
.vitem &$spam_bar$&
A string consisting of a number of &"+"& or &"-"& characters, representing the
.cindex "content scanning" "MIME parts"
.cindex "MIME content scanning"
.cindex "&%acl_smtp_mime%&"
+.cindex "&%acl_not_smtp_mime%&"
The &%acl_smtp_mime%& global option specifies an ACL that is called once for
each MIME part of an SMTP message, including multipart types, in the sequence
of their position in the message. Similarly, the &%acl_not_smtp_mime%& option
addresses, you should get a return code of zero.
-.new
.vitem &*pid_t&~child_open_exim2(int&~*fd,&~uschar&~*sender,&~uschar&~&&&
*sender_authentication)*&
This function is a more sophisticated version of &'child_open()'&. The command
&`exim -t -oem -oi -f `&&'sender'&&` -oMas `&&'sender_authentication'&
.endd
The third argument may be NULL, in which case the &%-oMas%& option is omitted.
-.wen
.vitem &*void&~debug_printf(char&~*,&~...)*&
.section "The Auto-Submitted: header line"
-.new
Whenever Exim generates an autoreply, a bounce, or a delay warning message, it
includes the header line:
-.wen
.code
Auto-Submitted: auto-replied
.endd
-H spool file is written) the earliest time at which delivery could start.
-.new
.section "The References: header line"
.cindex "&'References:'& header line"
Messages created by the &(autoreply)& transport include a &'References:'&
than 12 message IDs are copied from the &'References:'& header line in the
incoming message. If there are more than 12, the first one and then the final
11 are copied, before adding the message ID of the incoming message.
-.wen
-.new
.section "Variable Envelope Return Paths (VERP)" "SECTverp"
.cindex "VERP"
.cindex "Variable Envelope Return Paths"
a separate copy of the message for each address may take substantially longer
than sending a single copy with many recipients (for which VERP cannot be
used).
-.wen
This is the original sender that was received with the message; it is not
necessarily the same as the outgoing return path.
.next
-.new
.cindex "log" "sender verify failure"
&%sender_verify_failure%&: If this selector is unset, the separate log line
that gives details of a sender verification failure is not written. Log lines
for the rejection of SMTP commands contain just &"sender verify failed"&, so
some detail is lost.
-.wen
.next
.cindex "log" "size rejection"
&%size_reject%&: A log line is written whenever a message is rejected because
.section "Cycling log files (exicyclog)" "SECTcyclogfil"
-.new
.cindex "log" "cycling local files"
.cindex "cycling logs"
.cindex "&'exicyclog'&"
&_mainlog.02_& and so on, up to the limit that is set in the script or by the
&%-k%& option. Log files whose numbers exceed the limit are discarded. Reject
logs are handled similarly.
-.wen
If the limit is greater than 99, the script uses 3-digit numbers such as
&_mainlog.001_&, &_mainlog.002_&, etc. If you change from a number less than 99
.vlist
.vitem "&%-acl%& <&'number'&> <&'length'&>"
-.new
This item is obsolete, and is not generated from Exim release 4.61 onwards;
&%-aclc%& and &%-aclm%& are used instead. However, &%-acl%& is still
recognized, to provide backward compatibility. In the old format, a line of
empty. The number identifies the variable. The length is the length of the data
string for the variable. The string itself starts at the beginning of the next
line, and is followed by a newline character. It may contain internal newlines.
-.wen
.vitem "&%-active_hostname%& <&'hostname'&>"
This is present if, when the message was received over SMTP, the value of
git://git.exim.org / exim.git / blobdiff