. Update the Copyright year (only) when changing content.
. /////////////////////////////////////////////////////////////////////////////
-.set previousversion "4.86"
+.set previousversion "4.87"
.include ./local_params
.set ACL "access control lists (ACLs)"
.set I " "
.macro copyyear
-2015
+2016
.endmacro
. /////////////////////////////////////////////////////////////////////////////
continuation lines is ignored. Each argument or data line is passed through the
string expansion mechanism, and the result is output. Variable values from the
configuration file (for example, &$qualify_domain$&) are available, but no
-message-specific values (such as &$sender_domain$&) are set, because no message
+message-specific values (such as &$message_exim_id$&) are set, because no message
is being processed (but see &%-bem%& and &%-Mset%&).
&*Note*&: If you use this mechanism to test lookups, and you change the data
exim '-D ABC = something' ...
.endd
&%-D%& may be repeated up to 10 times on a command line.
-.new
Only macro names up to 22 letters long can be set.
-.wen
.vitem &%-d%&<&'debug&~options'&>
PostgreSQL database. See section &<<SECTsql>>&.
.next
-.new
.cindex "Redis lookup type"
.cindex lookup Redis
&(redis)&: The format of the query is an SQL statement that is passed to a
Redis database. See section &<<SECTsql>>&.
-.wen
.next
.cindex "sqlite lookup type"
The form if &"retry_VAL"& where VAL is an integer.
The default count is set by the main configuration option &%dns_retry%&.
-.new
.cindex cacheing "of dns lookup"
.cindex TTL "of dns lookup"
.cindex DNS TTL
Dnsdb lookup results are cached within a single process (and its children).
The cache entry lifetime is limited to the smallest time-to-live (TTL)
value of the set of returned DNS records.
-.wen
.section "Pseudo dnsdb record types" "SECID66"
found, but that is still a successful query. In other words, the list of
servers provides a backup facility, not a list of different places to look.
-.new
For Redis the global option need not be specified if all queries contain their
own server information &-- see section &<<SECTspeserque>>&.
If specified, the option must be set to a colon-separated list of server
.next
The password is optional; if present it is used to authenticate to the backend
.endlist
-.wen
-.new
The &%quote_mysql%&, &%quote_pgsql%&, and &%quote_oracle%& expansion operators
convert newline, tab, carriage return, and backspace to \n, \t, \r, and \b
respectively, and the characters single-quote, double-quote, and backslash
The &%quote_redis%& expansion operator
escapes whitespace and backslash characters with a backslash.
-.wen
.section "Specifying the server in the query" "SECTspeserque"
For MySQL, PostgreSQL and Redis lookups (but not currently for Oracle and InterBase),
For MySQL, an empty host name or the use of &"localhost"& in &%mysql_servers%&
causes a connection to the server on the local host by means of a Unix domain
socket. An alternate socket can be specified in parentheses.
-.new
An option group name for MySQL option files can be specified in square brackets;
the default value is &"exim"&.
-.wen
The full syntax of each item in &%mysql_servers%& is:
.display
<&'hostname'&>::<&'port'&>(<&'socket name'&>)[<&'option group'&>]/&&&
-.new
.vitem &*${imapfolder{*&<&'foldername'&>&*}}*&
.cindex expansion "imap folder"
.cindex "&%imapfolder%& expansion item"
This item converts a (possibly multilevel, or with non-ASCII characters)
folder specification to a Maildir name for filesystem use.
For information on internationalisation support see &<<SECTi18nMDA>>&.
-.wen
identifiers, base-36 digits. The number is converted to decimal and output as a
string.
-.new
.vitem &*${base64:*&<&'string'&>&*}*&
.cindex "expansion" "base64 encoding"
.cindex "base64 encoding" "in string expansion"
.cindex "base64 decoding" "in string expansion"
.cindex "&%base64d%& expansion item"
This operator converts a base64-encoded string into the un-coded form.
-.wen
.vitem &*${domain:*&<&'string'&>&*}*&
byte value 127 is converted to &`\x7f`&.
-.new
.vitem &*${ipv6denorm:*&<&'string'&>&*}*&
.cindex "&%ipv6denorm%& expansion item"
.cindex "IP address" normalisation
set of zero-valued groups is replaced with a double colon.
A trailing ipv4-style dotted-decimal set is converted to hex.
Pure IPv4 addresses are converted to IPv4-mapped IPv6.
-.wen
.vitem &*${lc:*&<&'string'&>&*}*&
.vitem &*${str2b64:*&<&'string'&>&*}*&
.cindex "&%str2b64%& expansion item"
-.new
Now deprecated, a synonym for the &%base64%& expansion operator.
-.wen
.cindex "&%utf8clean%& expansion item"
This replaces any invalid utf-8 sequence in the string by the character &`?`&.
-.new
.vitem "&*${utf8_domain_to_alabel:*&<&'string'&>&*}*&" &&&
"&*${utf8_domain_from_alabel:*&<&'string'&>&*}*&" &&&
"&*${utf8_localpart_to_alabel:*&<&'string'&>&*}*&" &&&
.cindex "&%utf8_localpart_from_alabel%& expansion item"
These convert EAI mail name components between UTF-8 and a-label forms.
For information on internationalisation support see &<<SECTi18nMTA>>&.
-.wen
.endlist
.vindex "&$config_file$&"
The name of the main configuration file Exim is using.
-.vitem &$demime_errorlevel$&
-.vindex "&$demime_errorlevel$&"
-This variable is available when Exim is compiled with
-the content-scanning extension and the obsolete &%demime%& condition. For
-details, see section &<<SECTdemimecond>>&.
-
-.vitem &$demime_reason$&
-.vindex "&$demime_reason$&"
-This variable is available when Exim is compiled with the
-content-scanning extension and the obsolete &%demime%& condition. For details,
-see section &<<SECTdemimecond>>&.
-
.vitem &$dkim_cur_signer$& &&&
&$dkim_verify_status$& &&&
&$dkim_verify_reason$& &&&
Then after a dot, the next group of digits is a minor version number.
There may be other characters following the minor version.
-.vitem &$found_extension$&
-.vindex "&$found_extension$&"
-This variable is available when Exim is compiled with the
-content-scanning extension and the obsolete &%demime%& condition. For details,
-see section &<<SECTdemimecond>>&.
-
.vitem &$header_$&<&'name'&>
This is not strictly an expansion variable. It is expansion syntax for
inserting the message header line with the given name. Note that the name must
qualified host name. See also &$smtp_active_hostname$&.
-.new
.vitem &$proxy_host_address$& &&&
&$proxy_host_port$& &&&
&$proxy_target_address$& &&&
These variables are only available when built with Proxy Protocol
or Socks5 support
For details see chapter &<<SECTproxyInbound>>&.
-.wen
-.new
.vitem &$prdr_requested$&
.cindex "PRDR" "variable for"
This variable is set to &"yes"& if PRDR was requested by the client for the
current message, otherwise &"no"&.
-.wen
.vitem &$prvscheck_address$&
This variable is used in conjunction with the &%prvscheck%& expansion item,
There is also a command line option &%-pd%& (for delay) which suppresses the
initial startup, even if &%perl_at_start%& is set.
+.new
+.ilist
+.oindex "&%perl_taintmode%&"
+.cindex "Perl" "taintmode"
+To provide more security executing Perl code via the embedded Perl
+interpeter, the &%perl_taintmode%& option can be set. This enables the
+taint mode of the Perl interpreter. You are encouraged to set this
+option to a true value. To avoid breaking existing installations, it
+defaults to false.
+.wen
+
.section "Calling Perl subroutines" "SECID86"
When the configuration file includes a &%perl_startup%& option you can make use
.table2
.row &%perl_at_start%& "always start the interpreter"
.row &%perl_startup%& "code to obey when starting Perl"
+.row &%perl_taintmode%& "enable taint mode in Perl"
.endtable
This option defines the ACL that is run when an SMTP VRFY command is
received. See chapter &<<CHAPACL>>& for further details.
-.new
.option add_environment main "string list" empty
.cindex "environment" "set values"
This option allows to set individual environment variables that the
currently linked libraries and programs in child processes use.
See &<<SECTpipeenv>>& for the environment of &(pipe)& transports.
-.wen
.option admin_groups main "string list&!!" unset
.cindex "admin user"
treated as if the &%bounce_return_size_limit%& (below) restriction was exceeded.
The option also applies to bounces returned when an error is detected
-during reception of a messsage.
+during reception of a message.
In this case lines from the original are truncated.
The option does not apply to messages generated by an &(autoreply)& transport.
not used.
-.new
.option event_action main string&!! unset
.cindex events
This option declares a string to be expanded for Exim's events mechanism.
For details see &<<CHAPevents>>&.
-.wen
.option exim_group main string "compile-time configured"
-.new
.option hosts_proxy main "host list&!!" unset
.cindex proxy "proxy protocol"
This option enables use of Proxy Protocol proxies for incoming
connections. For details see &<<SECTproxyInbound>>&.
-.wen
.option hosts_treat_as_local main "domain list&!!" unset
.option ignore_fromline_local main boolean false
See &%ignore_fromline_hosts%& above.
-.new
.option keep_environment main "string list" unset
.cindex "environment" "values from"
This option contains a string list of environment variables to keep.
environment variables to a fixed value. The environment for &(pipe)&
transports is handled separately, see section &<<SECTpipeenv>>& for
details.
-.wen
.option keep_malformed main time 4d
.option perl_at_start main boolean false
+.cindex "Perl"
This option is available only when Exim is built with an embedded Perl
interpreter. See chapter &<<CHAPperl>>& for details of its use.
.option perl_startup main string unset
+.cindex "Perl"
This option is available only when Exim is built with an embedded Perl
interpreter. See chapter &<<CHAPperl>>& for details of its use.
+.option perl_startup main boolean false
+.cindex "Perl"
+This Option enables the taint mode of the embedded Perl interpreter.
+
.option pgsql_servers main "string list" unset
.cindex "PostgreSQL lookup type" "server list"
.endd
-.new
.option smtputf8_advertise_hosts main "host list&!!" *
.cindex "SMTPUTF8" "advertising"
When Exim is built with support for internationalised mail names,
the availability therof is advertised in
response to EHLO only to those client hosts that match this option. See
chapter &<<CHAPi18n>>& for details of Exim's support for internationalisation.
-.wen
.option spamd_address main string "see below"
unfortunately not all, operating systems.
-.new
.option tls_advertise_hosts main "host list&!!" *
-.wen
.cindex "TLS" "advertising"
.cindex "encryption" "on SMTP connection"
.cindex "SMTP" "encrypted connection"
of the STARTTLS command to set up an encrypted session is advertised in
response to EHLO only to those client hosts that match this option. See
chapter &<<CHAPTLS>>& for details of Exim's support for TLS.
-.new
Note that the default value requires that a certificate be supplied
using the &%tls_certificate%& option. If no certificate is available then
the &%tls_advertise_hosts%& option should be set empty.
-.wen
.option tls_certificate main string&!! unset
status proof for the server's certificate, as obtained from the
Certificate Authority.
-.new
Usable for GnuTLS 3.4.4 or 3.3.17 or OpenSSL 1.1.0 (or later).
-.wen
.option tls_on_connect_ports main "string list" unset
.cindex events
This option declares a string to be expanded for Exim's events mechanism.
For details see &<<CHAPevents>>&.
-.wen
.option group transports string&!! "Exim group"
to ensure that any additional groups associated with the uid are set up.
-.new
.option max_parallel transports integer&!! unset
.cindex limit "transport parallelism"
.cindex transport "parallel processes"
start with &_misc_& and they are kept in the &_spool/db_& directory. There
may be one or two files, depending on the type of DBM in use. The same files
are used for ETRN and smtp transport serialization.
-.wen
.option message_size_limit transports string&!! 0
This option sets up a filtering (in the Unix shell sense) process for messages
at transport time. It should not be confused with mail filtering as set up by
individual users or via a system filter.
-.new
If unset, or expanding to an empty string, no filtering is done.
-.wen
When the message is about to be written out, the command specified by
&%transport_filter%& is started up in a separate, parallel process, and
delivery, the two pipe transports may be run concurrently. You must ensure that
any pipe commands you set up are robust against this happening. If the commands
write to a file, the &%exim_lock%& utility might be of use.
-.new
Alternatively the &%max_parallel%& option could be used with a value
of "1" to enforce serialization.
-.wen
may be one or two files, depending on the type of DBM in use. The same files
are used for ETRN serialization.
-.new
See also the &%max_parallel%& generic transport option.
-.wen
.option size_addition smtp integer 1024
the use of the SIZE option altogether.
-.new
.option socks_proxy smtp string&!! unset
.cindex proxy SOCKS
This option enables use of SOCKS proxies for connections made by the
transport. For details see &<<SECTproxySOCKS>>&.
-.wen
.option tls_certificate smtp string&!! unset
proof expires. The downside is that it requires server support.
Unless Exim is built with the support disabled,
-.new
or with GnuTLS earlier than version 3.3.16 / 3.4.8
-.wen
support for OCSP stapling is included.
There is a global option called &%tls_ocsp_file%&.
session, and indeed is required to issue a new EHLO or HELO after successfully
setting up encryption following a STARTTLS command.
-.new
Note also that a deny neither forces the client to go away nor means that
mail will be refused on the connection. Consider checking for
&$sender_helo_name$& being defined in a MAIL or RCPT ACL to do that.
-.wen
If the command is accepted by an &%accept%& verb that has a &%message%&
modifier, the message may not contain more than one line (it will be truncated
PRDR may be used to support per-user content filtering. Without it
one must defer any recipient after the first that has a different
content-filter configuration. With PRDR, the RCPT-time check
-.new
.cindex "PRDR" "variable for"
for this can be disabled when the variable &$prdr_requested$&
is &"yes"&.
-.wen
Any required difference in behaviour of the main DATA-time
ACL should however depend on the PRDR-time ACL having run, as Exim
will avoid doing so in some situations (e.g. single-recipient mails).
An attempt to set this option for any recipient but the first
for a mail will be quietly ignored.
If a recipient-verify callout
-.new
(with use_sender)
-.wen
connection is subsequently
requested in the same ACL it is held open and used for
any subsequent recipients and the data,
modified by any of the post-data ACLs (DATA, MIME and DKIM).
Headers may be modified by routers (subject to the above) and transports.
-.new
All the usual ACLs are called; if one results in the message being
rejected, all effort spent in delivery (including the costs on
the ultimate destination) will be wasted.
Note that in the case of data-time ACLs this includes the entire
message body.
-.wen
Cutthrough delivery is not supported via transport-filters or when DKIM signing
of outgoing messages is done, because it sends data to the ultimate destination
&*Note:*& This control applies only to the current message, not to any others
that are being submitted at the same time using &%-bs%& or &%-bS%&.
-.new
.vitem &*control&~=&~utf8_downconvert*&
This control enables conversion of UTF-8 in message addresses
to a-label form.
For details see &<<SECTi18nMTA>>&.
-.wen
.endlist vlist
problems such as a syntax error or a memory shortage. For more details, see
chapter &<<CHAPexiscan>>&.
-.vitem &*demime&~=&~*&<&'extension&~list'&>
-.cindex "&%demime%& ACL condition"
-This condition is available only when Exim is compiled with the
-content-scanning extension. Its use is described in section
-&<<SECTdemimecond>>&.
-
.vitem &*dnslists&~=&~*&<&'list&~of&~domain&~names&~and&~other&~data'&>
.cindex "&%dnslists%& ACL condition"
.cindex "DNS list" "in ACL"
.cindex cacheing "of dns lookup"
.cindex DNS TTL
DNS list lookups are cached by Exim for the duration of the SMTP session
-.new
(but limited by the DNS return TTL value),
-.wen
so a lookup based on the IP address is done at most once for any incoming
connection (assuming long-enough TTL).
Exim does not share information between multiple incoming
Two new main configuration options: &%av_scanner%& and &%spamd_address%&.
.endlist
-There is another content-scanning configuration option for &_Local/Makefile_&,
-called WITH_OLD_DEMIME. If this is set, the old, deprecated &%demime%& ACL
-condition is compiled, in addition to all the other content-scanning features.
-
Content-scanning is continually evolving, and new features are still being
added. While such features are still unstable and liable to incompatible
changes, they are made available in Exim by setting options whose names begin
parts of documentation are now available in English. You can get it at
&url(http://linux.mks.com.pl/). The only option for this scanner type is
the maximum number of processes used simultaneously to scan the attachments,
-provided that the demime facility is employed and also provided that mksd has
+provided that mksd has
been run with at least the same number of child processes. For example:
.code
av_scanner = mksd:2
&%message%& modifier that specifies the error returned to the sender, and/or in
logging data.
-If your virus scanner cannot unpack MIME and TNEF containers itself, you should
-use the &%demime%& condition (see section &<<SECTdemimecond>>&) before the
-&%malware%& condition.
-
Beware the interaction of Exim's &%message_size_limit%& with any size limits
imposed by your anti-virus scanner.
Here is a very simple scanning example:
.code
deny message = This message contains malware ($malware_name)
- demime = *
malware = *
.endd
The next example accepts messages when there is a problem with the scanner:
.code
deny message = This message contains malware ($malware_name)
- demime = *
malware = */defer_ok
.endd
The next example shows how to use an ACL variable to scan with both sophie and
&*Warning*&: With large messages, these conditions can be fairly
CPU-intensive.
-
-
-
-.section "The demime condition" "SECTdemimecond"
-.cindex "content scanning" "MIME checking"
-.cindex "MIME content scanning"
-The &%demime%& ACL condition provides MIME unpacking, sanity checking and file
-extension blocking. It is usable only in the DATA and non-SMTP ACLs. The
-&%demime%& condition uses a simpler interface to MIME decoding than the MIME
-ACL functionality, but provides no additional facilities. Please note that this
-condition is deprecated and kept only for backward compatibility. You must set
-the WITH_OLD_DEMIME option in &_Local/Makefile_& at build time to be able to
-use the &%demime%& condition.
-
-The &%demime%& condition unpacks MIME containers in the message. It detects
-errors in MIME containers and can match file extensions found in the message
-against a list. Using this facility produces files containing the unpacked MIME
-parts of the message in the temporary scan directory. If you do antivirus
-scanning, it is recommended that you use the &%demime%& condition before the
-antivirus (&%malware%&) condition.
-
-On the right-hand side of the &%demime%& condition you can pass a
-colon-separated list of file extensions that it should match against. For
-example:
-.code
-deny message = Found blacklisted file attachment
- demime = vbs:com:bat:pif:prf:lnk
-.endd
-If one of the file extensions is found, the condition is true, otherwise it is
-false. If there is a temporary error while demimeing (for example, &"disk
-full"&), the condition defers, and the message is temporarily rejected (unless
-the condition is on a &%warn%& verb).
-
-The right-hand side is expanded before being treated as a list, so you can have
-conditions and lookups there. If it expands to an empty string, &"false"&, or
-zero (&"0"&), no demimeing is done and the condition is false.
-
-The &%demime%& condition set the following variables:
-
-.vlist
-.vitem &$demime_errorlevel$&
-.vindex "&$demime_errorlevel$&"
-When an error is detected in a MIME container, this variable contains the
-severity of the error, as an integer number. The higher the value, the more
-severe the error (the current maximum value is 3). If this variable is unset or
-zero, no error occurred.
-
-.vitem &$demime_reason$&
-.vindex "&$demime_reason$&"
-When &$demime_errorlevel$& is greater than zero, this variable contains a
-human-readable text string describing the MIME error that occurred.
-.endlist
-
-.vlist
-.vitem &$found_extension$&
-.vindex "&$found_extension$&"
-When the &%demime%& condition is true, this variable contains the file
-extension it found.
-.endlist
-
-Both &$demime_errorlevel$& and &$demime_reason$& are set by the first call of
-the &%demime%& condition, and are not changed on subsequent calls.
-
-If you do not want to check for file extensions, but rather use the &%demime%&
-condition for unpacking or error checking purposes, pass &"*"& as the
-right-hand side value. Here is a more elaborate example of how to use this
-facility:
-.code
-# Reject messages with serious MIME container errors
-deny message = Found MIME error ($demime_reason).
- demime = *
- condition = ${if >{$demime_errorlevel}{2}{1}{0}}
-
-# Reject known virus spreading file extensions.
-# Accepting these is pretty much braindead.
-deny message = contains $found_extension file (blacklisted).
- demime = com:vbs:bat:pif:scr
-
-# Freeze .exe and .doc files. Postmaster can
-# examine them and eventually thaw them.
-deny log_message = Another $found_extension file.
- demime = exe:doc
- control = freeze
-.endd
.ecindex IIDcosca
runs the ACL specified by &%acl_smtp_vrfy%& or &%acl_smtp_expn%& (as
appropriate) in order to decide whether the command should be accepted or not.
-.new
.cindex "VRFY" "processing"
When no ACL is defined for VRFY, or if it rejects without
setting an explicit response code, the command is accepted
(with a 252 SMTP response code)
in order to support awkward clients that do a VRFY before every RCPT.
-.wen
When VRFY is accepted, it runs exactly the same code as when Exim is
called with the &%-bv%& option, and returns 250/451/550
SMTP response codes.
&` incoming_interface `& local interface on <= and => lines
&` incoming_port `& remote port on <= lines
&`*lost_incoming_connection `& as it says (includes timeouts)
-.new
&` outgoing_interface `& local interface on => lines
-.wen
&` outgoing_port `& add remote port to => lines
&`*queue_run `& start and end queue runs
&` queue_time `& time on queue for one recipient
&` queue_time_overall `& time on queue for whole message
&` pid `& Exim process id
-.new
&` proxy `& proxy address on <= and => lines
-.wen
&` received_recipients `& recipients on <= lines
&` received_sender `& sender on <= lines
&`*rejected_header `& header contents on reject log
followed by a colon and the port number. The local interface and port are also
added to other SMTP log lines, for example &"SMTP connection from"&, to
rejection lines, and (despite the name) to outgoing &"=>"& and &"->"& lines.
-.new
The latter can be disabled by turning off the &%outgoing_interface%& option.
-.wen
.next
-.new
.cindex log "incoming proxy address"
.cindex proxy "logging proxy address"
.cindex "TCP/IP" "logging proxy address"
on a proxied connection
or the &"=>"& line for a message delivered on a proxied connection..
See &<<SECTproxyInbound>>& for more information.
-.wen
.next
.cindex "log" "incoming remote port"
.cindex "port" "logging remote"
.cindex "log" "local address and port"
.cindex "TCP/IP" "logging local address and port"
.cindex "interface" "logging"
-.new
&%outgoing_interface%&: If &%incoming_interface%& is turned on, then the
interface on which a message was sent is added to delivery lines as an I= tag
followed by IP address in square brackets. You can disable this by turning
off the &%outgoing_interface%& option.
-.wen
.next
.cindex "log" "outgoing remote port"
.cindex "port" "logging outgoint remote"
.cindex "TCP/IP" "logging ougtoing remote port"
&%outgoing_port%&: The remote port number is added to delivery log lines (those
containing => tags) following the IP address.
-.new
The local port is also added if &%incoming_interface%& and
&%outgoing_interface%& are both enabled.
-.wen
This option is not included in the default setting, because for most ordinary
configurations, the remote port number is always 25 (the SMTP port), and the
local port is a random ephemeral port.
be tracked on a per-domain basis, rather than merely upon source IP address.
DKIM is documented in RFC 4871.
-.new
DKIM support is compiled into Exim by default if TLS support is present.
-.wen
It can be disabled by setting DISABLE_DKIM=yes in &_Local/Makefile_&.
Exim's DKIM implementation allows to
.cindex "proxy support"
.cindex "proxy" "access via"
-.new
A proxy is an intermediate system through which communication is passed.
Proxies may provide a security, availability or load-distribution function.
To log the (local) IP of a proxy in the incoming or delivery logline,
add &"+proxy"& to the &%log_selector%& option.
This will add a component tagged with &"PRX="& to the line.
-.wen
. ////////////////////////////////////////////////////////////////////////////
. ////////////////////////////////////////////////////////////////////////////
.cindex i18n
.cindex UTF-8 "mail name handling"
-.new
Exim has support for Internationalised mail names.
To include this it must be built with SUPPORT_I18N and the libidn library.
Standards supported are RFCs 2060, 5890, 6530 and 6533.
Note that the source charset setting is vital, and also that characters
must be representable in UTF-16.
-.wen
. ////////////////////////////////////////////////////////////////////////////
. ////////////////////////////////////////////////////////////////////////////
"Events"
.cindex events
-.new
The events mechanism in Exim can be used to intercept processing at a number
of points. It was originally invented to giave a way to do customised logging
actions (for example, to a database) but can also be used to modify some
chain element received on the connection.
For OpenSSL it will trigger for every chain element including those
loaded locally.
-.wen
. ////////////////////////////////////////////////////////////////////////////
. ////////////////////////////////////////////////////////////////////////////
git://git.exim.org / users / jgh / exim.git / blobdiff