-.section "Dynamically loaded lookup module support" "SECTdynamicmodules"
+.section "Dynamically loaded module support" "SECTdynamicmodules"
.cindex "lookup modules"
+.cindex "router modules"
+.cindex "transport modules"
+.cindex "authenticator modules"
.cindex "dynamic modules"
.cindex ".so building"
On some platforms, Exim supports not compiling all lookup types directly into
the main binary, instead putting some into external modules which can be loaded
on demand.
This permits packagers to build Exim with support for lookups with extensive
-library dependencies without requiring all users to install all of those
+library dependencies without requiring all systems to install all of those
dependencies.
-Most, but not all, lookup types can be built this way.
+.new
+Any combination of lookup types can be built this way.
+Lookup types that provide several variants will be loaded as
+Exim starts.
+Types that provide only one method are not loaded until used by
+the runtime configuration.
+.wen
-Set &`LOOKUP_MODULE_DIR`& to the directory into which the modules will be
+For building
+set &`LOOKUP_MODULE_DIR`& to the directory into which the modules will be
installed; Exim will only load modules from that directory, as a security
measure. You will need to set &`CFLAGS_DYNAMIC`& if not already defined
for your OS; see &_OS/Makefile-Linux_& for an example.
Then, for each module to be loaded dynamically, define the relevant
&`LOOKUP_`&<&'lookup_type'&> flags to have the value "2" instead of "yes".
For example, this will build in lsearch but load sqlite and mysql support
-on demand:
+only if each is installed:
.code
LOOKUP_LSEARCH=yes
LOOKUP_SQLITE=2
LOOKUP_MYSQL=2
.endd
+Set also &`LOOKUP_`&<&'lookup_type'&>&` INCLUDE`& and
+&`LOOKUP_`&<&'lookup_type'&>`_LIBS if needed for each lookup type,
+ensuring that duplicates are not present in more global values.
+
+.new
+Similarly, authenticator, router and transport drivers can be built
+as external modules.
+Modules will be searched for as demanded by the runtime configuration,
+permitting a smaller Exim binary.
+
+For building, as above but using
+&`AUTH_*`&, &`ROUTER_*`& and &`TRANSPORT_*`& instead of &`LOOKUP_*`&,
+.wen
.section "The building process" "SECID29"
colon in the example above are necessary. If they were not there, the list would
be interpreted as the two items 127.0.0.1:: and 1.
-.section "Changing list separators" "SECTlistsepchange"
+.subsection "Changing list separators" "SECTlistsepchange"
.cindex "list separator" "changing"
.cindex "IPv6" "addresses in lists"
Doubling colons in IPv6 addresses is an unwelcome chore, so a mechanism was
-.section "Empty items in lists" "SECTempitelis"
+.subsection "Empty items in lists" "SECTempitelis"
.cindex "list" "empty item in"
An empty item at the end of a list is always ignored. In other words, trailing
separator characters are ignored. Thus, the list in
The new version avoids issues with tainted
arguments explicitly expanded as part of the query.
The entire string within the braces becomes tainted,
-including the server sepcification - which is not permissible.
+including the server specification - which is not permissible.
If the older sytax is used, a warning message will be logged.
This syntax will be removed in a future release.
.vitem &*${srs_encode&~{*&<&'secret'&>&*}{*&<&'return&~path'&>&*}{*&<&'original&~domain'&>&*}}*&
-SRS encoding. See SECT &<<SECTSRS>>& for details.
+SRS encoding. See section &<<SECTSRS>>& for details.
.vindex "&$config_file$&"
The name of the main configuration file Exim is using.
+.vitem &$connection_id$&
+.vindex "&$connection_id$&"
+.cindex connection "identifier logging"
+An identifier for the accepted connection, for use in custom logging.
+
.vitem &$dkim_verify_status$&
Results of DKIM verification.
For details see section &<<SECDKIMVFY>>&.
.option acl_smtp_etrn main string&!! unset
.cindex "ETRN" "ACL for"
+.cindex "ETRN" advertisement
This option defines the ACL that is run when an SMTP ETRN command is
-received. See chapter &<<CHAPACL>>& for further details.
+received.
+If no value is set then the ETRN facility is not advertised.
+See chapter &<<CHAPACL>>& for further details.
.option acl_smtp_expn main string&!! unset
.cindex "EXPN" "ACL for"
See section &<<SECDKIMVFY>>&.
-.option dmarc_forensic_sender main string&!! unset &&&
- dmarc_history_file main string unset &&&
- dmarc_tld_file main string unset
+.options dmarc_forensic_sender main string&!! unset &&&
+ dmarc_history_file main string unset &&&
+ dmarc_tld_file main string unset
.cindex DMARC "main section options"
These options control DMARC processing.
See section &<<SECDMARC>>& for details.
. Allow this long option name to split; give it unsplit as a fifth argument
. for the automatic .oindex that is generated by .option.
+. WAS:
+. .option "extract_addresses_remove_ &~&~arguments"
+. but apparently this results in searchability problems; bug 1197
-.option "extract_addresses_remove_arguments" main boolean true &&&
- extract_addresses_remove_arguments
+.option extract_addresses_remove_arguments main boolean true
.oindex "&%-t%&"
.cindex "command line" "addresses with &%-t%&"
.cindex "Sendmail compatibility" "&%-t%& option"
.cindex "underscore in EHLO/HELO"
This option can be set to a string of rogue characters that are permitted in
non-ip-literal EHLO and HELO names in addition to the standard letters, digits,
-hyphens, and dots. For examplem if you really must allow underscores,
+hyphens, and dots. For example if you really must allow underscores,
you can set
.code
helo_allow_chars = _
.cindex "ESMTP extensions" LIMITS
This option can be used to suppress the advertisement of the SMTP
LIMITS extension (RFC 9422) to specific hosts.
-If permitted, Exim as a servier will advertise in the EHLO response
+If permitted, Exim as a server will advertise in the EHLO response
the limit for RCPT commands set by the &%recipients_max%& option (if it is set)
and the limit for MAIL commands set by the &%smtp_accept_max_per_connection%&
option.
The SMTP service extension keyword advertised is &"PIPECONNECT"&;
it permits the client to pipeline
-TCP connection and hello command (inclear phase),
+TCP connection and hello command (cleatext phase),
or TLS-establishment and hello command (encrypted phase),
on later connections to the same host.
. searchable. NM changed this occurrence for bug 1197 to no longer allow
. the option name to split.
-.option "smtp_accept_max_per_connection" main integer&!! 1000 &&&
- smtp_accept_max_per_connection
+.option smtp_accept_max_per_connection main integer&!! 1000
.cindex "SMTP" "limiting incoming message count"
.cindex "limit" "messages per SMTP connection"
The value of this option limits the number of MAIL commands that Exim is
. See the comment on smtp_accept_max_per_connection
-.option "smtp_accept_queue_per_connection" main integer 10 &&&
- smtp_accept_queue_per_connection
+.option smtp_accept_queue_per_connection main integer 10
.cindex "queueing incoming messages"
.cindex "message" "queueing by message count"
This option limits the number of delivery processes that Exim starts
and are rewritten according to the global rewriting rules.
+.option sieve_inbox redirect string&!! inbox
+.new
+The value of this option is passed to a Sieve filter to specify the
+name of the mailbox used for "keep" operations (explicit or implicit).
+.wen
+
.option sieve_subaddress redirect string&!! unset
The value of this option is passed to a Sieve filter to specify the
:subaddress part of an address.
.endd
In this situation, the expansion of &%file%& or &%directory%& in the transport
must transform the relative path into an appropriate absolute filename. In the
-case of Sieve filters, the name &'inbox'& must be handled. It is the name that
+case of Sieve filters, the name &'inbox'& must be handled. It is the
+.new
+default
+.wen
+name that
is used as a result of a &"keep"& action in the filter. This example shows one
way of handling this requirement:
.code
location, absolute paths are used without change, and other folders are in the
&_mail_& directory within the home directory.
+.new
+An alternative for the &"keep"& aspect is to use the &%sieve_inbox%& option
+on the redirect router that calls the Sieve filter,
+to explicitly set the filename used.
+.wen
+
&*Note 1*&: While processing an Exim filter, a relative path such as
&_folder23_& is turned into an absolute path if a home directory is known to
the router. In particular, this is the case if &%check_local_user%& is set. If
&*Note 2*&: An absolute path in &$address_file$& is not treated specially;
the &%file%& or &%directory%& option is still used if it is set.
+.new
+&*Note 3*&: Permitting a user to enable writes to an absolute path
+may be a security issue.
+.wen
the operation and configuration of DKIM, see section &<<SECDKIM>>&.
-.vitem &*control&~=&~dmarc_disable_verify*&
+.vitem &*control&~=&~dmarc_disable_verify*& &&&
+ &*control&~=&~dmarc_enable_forensic*&
.cindex "disable DMARC verify"
-.cindex "DMARC" "disable verify"
-This control turns off DMARC verification processing entirely. For details on
+.cindex DMARC "disable verify"
+.cindex DMARC controls
+.cindex DMARC "forensic mails"
+These control affect DMARC processing. For details on
the operation and configuration of DMARC, see section &<<SECDMARC>>&.
+The &"disable"& turns off DMARC verification processing entirely.
+
.vitem &*control&~=&~dscp/*&<&'value'&>
.cindex "&ACL;" "setting DSCP value"
.vitem &*void&~debug_printf(char&~*,&~...)*&
-This is Exim's debugging function, with arguments as for &'(printf()'&. The
+This is Exim's debugging function, with arguments as for &'printf()'&. The
output is written to the standard error stream. If no debugging is selected,
calls to &'debug_printf()'& have no effect. Normally, you should make calls
conditional on the &`local_scan`& debug selector by coding like this:
.cindex "SMTP" "batching over TCP/IP"
When a message is successfully delivered over a TCP/IP SMTP connection, Exim
looks in the hints database for the transport to see if there are any queued
-messages waiting for the host to which it is connected. If it finds one, it
-creates a new Exim process using the &%-MC%& option (which can only be used by
-a process running as root or the Exim user) and passes the TCP/IP socket to it
-so that it can deliver another message using the same socket. The new process
-does only those deliveries that are routed to the connected host, and may in
-turn pass the socket on to a third process, and so on.
+messages waiting for the host to which it is connected.
+If it finds one, it arranges to attempt that message on the same connection.
The &%connection_max_messages%& option of the &(smtp)& transport can be used to
limit the number of messages sent down a single TCP/IP connection.
.subsection "The ETRN command" SECTETRN
.cindex "ETRN" "processing"
.cindex "ESMTP extensions" ETRN
+Most modern installations never need to use this.
+It is used for managing messages queued for an intermittently-connecting
+destination (eg. one using a dialup connection).
+
+.oindex "&%acl_smtp_etrn%&"
+The command is only available if permitted by an ACL
+specfied by the main-section &%acl_smtp_etrn%& option.
+
RFC 1985 describes an ESMTP command called ETRN that is designed to
overcome the security problems of the TURN command (which has fallen into
disuse). When Exim receives an ETRN command on a TCP/IP connection, it runs
only way to log such cases is to interpose a script such as &_util/logargs.sh_&
between the caller and Exim.
.next
-.cindex "log" "connection identifier"
-&%connection_identifier%&: An identifier for the accepted connection is added to
+.cindex log "connection identifier"
+.cindex connection "identifier logging"
+&%connection_id%&: An identifier for the accepted connection is added to
connection start and end lines and to message accept lines.
The identifier is tagged by Ci=.
The value is PID-based, so will reset on reboot and will wrap.
.next
-.cindex "log" "connection rejections"
+.cindex log "connection rejections"
+.cindex connection "rejection logging"
&%connection_reject%&: A log entry is written whenever an incoming SMTP
connection is rejected, for whatever reason.
.next
-.cindex "log" "delayed delivery"
+.cindex log "delayed delivery"
.cindex "delayed delivery, logging"
&%delay_delivery%&: A log entry is written whenever a delivery process is not
started for an incoming message because the load is too high or too many
The &'misc'& database is used for
.ilist
-Serializing ETRN runs (when &%smtp_etrn_serialize%& is set)
-.next
Serializing delivery to a specific host (when &%serialize_hosts%& is set in an
&(smtp)& transport)
.next
in a transport)
.next
Recording EHLO-time facilities advertised by hosts
+.next
+Serializing ETRN runs (when &%smtp_etrn_serialize%& is set)
.endlist
-.section "exim_dumpdb" "SECTdumpdb"
+.subsection "exim_dumpdb" "SECTdumpdb"
.cindex "&'exim_dumpdb'&"
The entire contents of a database are written to the standard output by the
&'exim_dumpdb'& program,
-.section "exim_tidydb" "SECTtidydb"
+.subsection "exim_tidydb" "SECTtidydb"
.cindex "&'exim_tidydb'&"
The &'exim_tidydb'& utility program is used to tidy up the contents of a hints
database. If run with no options, it removes all records that are more than 30
-.section "exim_fixdb" "SECTfixdb"
+.subsection "exim_fixdb" "SECTfixdb"
.cindex "&'exim_fixdb'&"
The &'exim_fixdb'& program is a utility for interactively modifying databases.
Its main use is for testing Exim, but it might also be occasionally useful for
.next
A queue runner process retains root privilege throughout its execution. Its
job is to fork a controlled sequence of delivery processes.
+
+.next
+A delivery process retains root privilege throughout most of its execution.,
+including while the recipient addresses in a message are being routed.
+
+.ilist
+However, if a user's filter file has to be processed,
+this is done in a subprocess that runs under the individual user's uid and
+gid. A system filter is run as root unless &%system_filter_user%& is set.
+.endlist
+
+Any actual deliveries (that is, the transports themselves) are run in
+subprocesses which always change to a non-root uid and gid.
+.ilist
+For local
+deliveries this is typically the uid and gid of the owner of the mailbox.
.next
-A delivery process retains root privilege throughout most of its execution,
-but any actual deliveries (that is, the transports themselves) are run in
-subprocesses which always change to a non-root uid and gid. For local
-deliveries this is typically the uid and gid of the owner of the mailbox; for
-remote deliveries, the Exim uid and gid are used. Once all the delivery
+For remote deliveries, the Exim uid and gid are used.
+.endlist
+
+Once all the delivery
subprocesses have been run, a delivery process changes to the Exim uid and gid
while doing post-delivery tidying up such as updating the retry database and
generating bounce and warning messages.
-While the recipient addresses in a message are being routed, the delivery
-process runs as root. However, if a user's filter file has to be processed,
-this is done in a subprocess that runs under the individual user's uid and
-gid. A system filter is run as root unless &%system_filter_user%& is set.
.next
A process that is testing addresses (the &%-bt%& option) runs as root so that
the routing is done in the same environment as a message delivery.
openssl genrsa -out dkim_rsa.private 2048
openssl rsa -in dkim_rsa.private -out /dev/stdout -pubout -outform PEM
.endd
-The result file from the first command should be retained, and
-this option set to use it.
+The result file from the first command should be retained,
+permissions set so that Exim can read it,
+and this option set to use it.
Take the base-64 lines from the output of the second command, concatenated,
for the DNS TXT record.
See section 3.6 of RFC6376 for the record specification.
SPF verification support is built into Exim if SUPPORT_SPF=yes is set in
&_Local/Makefile_&. The support uses the &_libspf2_& library
&url(https://www.libspf2.org/).
+.new
+.cindex "dynamic modules"
+The support can be built as a dynamic-load module if desired;
+see the comments in that Makefile.
+.wen
+
There is no Exim involvement in the transmission of messages;
publishing certain DNS records is all that is required.
The name is placed in the variable &$event_name$& and the event action
expansion must check this, as it will be called for every possible event type.
+.new
The current list of events is:
.itable all 0 0 4 25* left 10* center 15* center 50* left
.row auth:fail after both "per driver per authentication attempt"
.row tls:fail:connect after main "per connection"
.row smtp:connect after transport "per connection"
.row smtp:ehlo after transport "per connection"
+.row smtp:fail:protocol after main "per connection"
+.row smtp:fail:syntax after main "per connection"
.endtable
+.wen
New event types may be added in future.
The event name is a colon-separated list, defining the type of
An additional variable, &$event_data$&, is filled with information varying
with the event type:
+.new
.itable all 0 0 2 20* left 80* left
.row auth:fail "smtp response"
.row dane:fail "failure reason"
.row tls:fail:connect "error string"
.row smtp:connect "smtp banner"
.row smtp:ehlo "smtp ehlo response"
+.row smtp:fail:protocol "error string"
+.row smtp:fail:syntax "error string"
.endtable
+.wen
The :defer events populate one extra variable: &$event_defer_errno$&.
git://git.exim.org / exim.git / blobdiff