. Update the Copyright year (only) when changing content.
. /////////////////////////////////////////////////////////////////////////////
-.set previousversion "4.94"
+.set previousversion "4.95"
.include ./local_params
.set ACL "access control lists (ACLs)"
.next
If the &%domains%& option is set, the domain of the address must be in the set
of domains that it defines.
-.new
.cindex "tainted data" "de-tainting"
A match verifies the variable &$domain$& (which carries tainted data)
and assigns an untainted value to the &$domain_data$& variable.
When an untainted value is wanted, use this option
rather than the generic &%condition%& option.
-.wen
.next
.vindex "&$local_part_prefix$&"
.cindex affix "router precondition"
If the &%local_parts%& option is set, the local part of the address must be in
the set of local parts that it defines.
-.new
A match verifies the variable &$local_part$& (which carries tainted data)
and assigns an untainted value to the &$local_part_data$& variable.
Such an untainted value is often needed in the transport.
When an untainted value is wanted, use this option
rather than the generic &%condition%& option.
-.wen
If &%local_part_prefix%& or
&%local_part_suffix%& is in use, the prefix or suffix is removed from the local
uses an expanded string to allow you to set up your own custom preconditions.
Expanded strings are described in chapter &<<CHAPexpand>>&.
-.new
Note that while using
this option for address matching technically works,
it does not set any de-tainted values.
for transport options.
Using the &%domains%& and &%local_parts%& options is usually the most
convenient way to obtain them.
-.wen
.endlist
by Exim in conjunction with the &%-MC%& option. It signifies that a
remote host supports the ESMTP &_CHUNKING_& extension.
-.new
.vitem &%-MCL%&
.oindex "&%-MCL%&"
This option is not intended for use by external callers. It is used internally
which Exim is connected advertised limits on numbers of mails, recipients or
recipient domains.
The limits are given by the following three arguments.
-.wen
.vitem &%-MCP%&
.oindex "&%-MCP%&"
by Exim in conjunction with the &%-MC%& option. It signifies that the server to
which Exim is connected supports pipelining.
-.new
.vitem &%-MCp%&
.oindex "&%-MCp%&"
This option is not intended for use by external callers. It is used internally
by Exim in conjunction with the &%-MC%& option. It signifies that the connection
t a remote server is via a SOCKS proxy, using addresses and ports given by
the following four arguments.
-.wen
.vitem &%-MCQ%&&~<&'process&~id'&>&~<&'pipe&~fd'&>
.oindex "&%-MCQ%&"
signals the final completion of the sequence of processes that are passing
messages through the same SMTP connection.
-.new
.vitem &%-MCq%&&~<&'recipient&~address'&>&~<&'size'&>
.oindex "&%-MCq%&"
This option is not intended for use by external callers. It is used internally
by Exim to implement quota checking for local users.
-.wen
.vitem &%-MCS%&
.oindex "&%-MCS%&"
by Exim in conjunction with the &%-MC%& option, and passes on the fact that the
host to which Exim is connected supports TLS encryption.
-.new
.vitem &%-MCr%&&~<&'SNI'&> &&&
&%-MCs%&&~<&'SNI'&>
.oindex "&%-MCs%&"
a TLS Server Name Indication was sent as part of the channel establishment.
The argument gives the SNI string.
The "r" variant indicates a DANE-verified connection.
-.wen
.vitem &%-MCt%&&~<&'IP&~address'&>&~<&'port'&>&~<&'cipher'&>
.oindex "&%-MCt%&"
in chapter &<<CHAPinterfaces>>&. When &%-oX%& is used to start a daemon, no pid
file is written unless &%-oP%& is also present to specify a pid filename.
-.new
.vitem &%-oY%&
.oindex &%-oY%&
.cindex "daemon notifier socket"
.next
obtaining a current queue size
.endlist
-.wen
.vitem &%-pd%&
.oindex "&%-pd%&"
first &%domains%& setting above generates the second setting, which therefore
causes a second lookup to occur.
-.new
The lookup type may optionally be followed by a comma
and a comma-separated list of options.
Each option is a &"name=value"& pair.
If this is given then the cache that Exim manages for lookup results
is not checked before doing the lookup.
The result of the lookup is still written to the cache.
-.wen
The rest of this chapter describes the different lookup types that are
available. Any of them can be used in any part of the configuration where a
IPv4, in dotted-quad form. (Exim converts IPv4-mapped IPv6 addresses to this
notation before executing the lookup.)
-.new
One option is supported, "ret=full", to request the return of the entire line
rather than omitting the key porttion.
Note however that the key portion will have been de-quoted.
-.wen
.next
.cindex lookup json
For elements of type string, the returned value is de-quoted.
-.new
.next
.cindex LMDB
.cindex lookup lmdb
You will need to separately create the LMDB database file,
possibly using the &"mdb_load"& utility.
-.wen
.next
of independent, short-lived processes, this caching applies only within a
single Exim process. There is no inter-process lookup caching facility.
-.new
If an option &"cache=no_rd"& is used on the lookup then
the cache is only written to, cached data is not used for the operation
and a real lookup is done.
-.wen
For single-key lookups, Exim keeps the relevant files open in case there is
another lookup that needs them. In some types of configuration this can lead to
addition to the SQL query. An SQLite database is a single file, and there is no
daemon as in the other SQL databases.
-.new
.oindex &%sqlite_dbfile%&
There are two ways of
specifying the file.
lookup type word. The option is the word &"file"&, then an equals,
then the filename.
The filename in this case cannot contain whitespace or open-brace charachters.
-.wen
A deprecated method is available, prefixing the query with the filename
separated by white space.
A &%local_parts%& router option or &%local_parts%& ACL condition
will store a result in the &$local_part_data$& variable.
.vitem domains
-.new
A &%domains%& router option or &%domains%& ACL condition
will store a result in the &$domain_data$& variable.
-.wen
.vitem senders
A &%senders%& router option or &%senders%& ACL condition
will store a result in the &$sender_data$& variable.
.cindex "tainted data" "de-tainting"
The value will be untainted.
-.new
&*Note*&: If the data result of the lookup (as opposed to the key)
is empty, then this empty value is stored in &$domain_data$&.
The option to return the key for the lookup, as the value,
may be what is wanted.
-.wen
.next
.cindex "tainted data" definition
.cindex expansion "tainted data"
and expansion of data deriving from the sender (&"tainted data"&)
-.new
is not permitted (including acessing a file using a tainted name).
The main config option &%allow_insecure_tainted_data%& can be used as
mitigation during uprades to more secure configurations.
-.wen
-.new
Common ways of obtaining untainted equivalents of variables with
tainted values
.cindex "tainted data" "de-tainting"
or the password file,
or accessed via a DBMS.
Specific methods are indexed under &"de-tainting"&.
-.wen
You can use &`fail`& instead of {<&'string3'&>} as in a string extract.
-.new
.vitem &*${listquote{*&<&'separator'&>&*}{*&<&'string'&>&*}}*&
.cindex quoting "for list"
.cindex list quoting
An empty string is replaced with a single space.
This converts the string into a safe form for use as a list element,
in a list using the given separator.
-.wen
.vitem "&*${lookup&~{*&<&'key'&>&*}&~*&<&'search&~type'&>&*&~&&&
-.new
.vitem &*${srs_encode&~{*&<&'secret'&>&*}{*&<&'return&~path'&>&*}{*&<&'original&~domain'&>&*}}*&
SRS encoding. See SECT &<<SECTSRS>>& for details.
-.wen
and selects address-, domain-, host- or localpart- lists to search among respectively.
Otherwise all types are searched in an undefined order and the first
matching list is returned.
-.new
&*Note*&: Neither string-expansion of lists referenced by named-list syntax elements,
nor expansion of lookup elements, is done by the &%listnamed%& operator.
-.wen
.vitem &*${local_part:*&<&'string'&>&*}*&
is done by calling the &[stat()]& function. The use of the &%exists%& test in
users' filter files may be locked out by the system administrator.
-.new
&*Note:*& Testing a path using this condition is not a sufficient way of
de-tainting it.
Consider using a dsearch lookup.
-.wen
.vitem &*first_delivery*&
.cindex "delivery" "first"
Case and collation order are defined per the system C locale.
-.new
.vitem &*inbound_srs&~{*&<&'local&~part'&>&*}{*&<&'secret'&>&*}*&
SRS decode. See SECT &<<SECTSRS>>& for details.
-.wen
.vitem &*inlist&~{*&<&'string1'&>&*}{*&<&'string2'&>&*}*& &&&
You can use &$acl_verify_message$& during the expansion of the &%message%& or
&%log_message%& modifiers, to include information about the verification
failure.
-.new
&*Note*&: The variable is cleared at the end of processing the ACL verb.
-.wen
.vitem &$address_data$&
.vindex "&$address_data$&"
.vitem &$domain_data$&
.vindex "&$domain_data$&"
When the &%domains%& condition on a router
-.new
or an ACL
matches a domain
against a list, the match value is copied to &$domain_data$&.
This is an enhancement over previous versions of Exim, when it only
applied to the data read by a lookup.
For details on match values see section &<<SECTlistresults>>& et. al.
-.wen
If the router routes the
address to a transport, the value is available in that transport. If the
.vindex "&$local_part_data$&"
When the &%local_parts%& condition on a router or ACL
matches a local part list
-.new
the match value is copied to &$local_part_data$&.
This is an enhancement over previous versions of Exim, when it only
applied to the data read by a lookup.
For details on match values see section &<<SECTlistresults>>& et. al.
-.wen
The &%check_local_user%& router option also sets this variable.
which is not the leaf.
-.new
.vitem &$tls_in_resumption$& &&&
&$tls_out_resumption$&
.vindex &$tls_in_resumption$&
.vindex &$tls_out_resumption$&
.cindex TLS resumption
Observability for TLS session resumption. See &<<SECTresumption>>& for details.
-.wen
.vitem &$tls_in_sni$&
option to a true value. To avoid breaking existing installations, it
defaults to false.
-.new
&*Note*&: This is entirely separate from Exim's tainted-data tracking.
-.wen
.section "Calling Perl subroutines" "SECID86"
configuration). This &"magic string"& matches the domain literal form of all
the local host's IP addresses.
-.new
.option allow_insecure_tainted_data main boolean false
.cindex "de-tainting"
.oindex "allow_insecure_tainted_data"
message rejection) into warnings. This option is meant as mitigation only
and deprecated already today. Future releases of Exim may ignore it.
The &%taint%& log selector can be used to suppress even the warnings.
-.wen
If the &%smtp_connection%& log selector is not set, this option has no effect.
-.new
.option hosts_require_alpn main "host list&!!" unset
.cindex ALPN "require negotiation in server"
.cindex TLS ALPN
&*Note*&: prevention of fallback to in-clear connection is not
managed by this option, and should be done separately.
-.wen
.option hosts_proxy main "host list&!!" unset
If the platform supports Linux-style abstract socket names, the result
is used with a nul byte prefixed.
Otherwise,
-.new "if nonempty,"
it should be a full path name and use a directory accessible
to Exim.
-.new
If this option is set as empty,
or the command line &%-oY%& option is used, or
-.wen
the command line uses a &%-oX%& option and does not use &%-oP%&,
then a notifier socket is not created.
See also the &%hosts_pipe_connect%& smtp transport option.
-.new
The SMTP service extension keyword advertised is &"PIPE_CONNECT"&.
-.wen
.option prdr_enable main boolean false
&%queue_list_requires_admin%& and &%commandline_checks_require_admin%&.
-.new
.option proxy_protocol_timeout main time 3s
.cindex proxy "proxy protocol"
This option sets the timeout for proxy protocol negotiation.
For details see section &<<SECTproxyInbound>>&.
-.wen
.option qualify_domain main string "see below"
next queue run. See also &%hold_domains%& and &%queue_smtp_domains%&.
-.new
.option queue_fast_ramp main boolean false
.cindex "queue runner" "two phase"
.cindex "queue" "double scanning"
command line, may start parallel delivery processes during their first
phase. This will be done when a threshold number of messages have been
routed for a single host.
-.wen
.option queue_list_requires_admin main boolean true
response is given to subsequent MAIL commands. This limit is a safety
precaution against a client that goes mad (incidents of this type have been
seen).
-.new
The option is expanded after the HELO or EHLO is received
and may depend on values available at that time.
An empty or zero value after expansion removes the limit.
-.wen
.option smtp_accept_max_per_host main string&!! unset
is not required the &%tls_advertise_hosts%& option should be set empty.
-.new
.option tls_alpn main "string list&!!" "smtp : esmtp"
.cindex TLS "Application Layer Protocol Names"
.cindex TLS ALPN
and the client offers either more than
ALPN name or a name which does not match the list,
the TLS connection is declined.
-.wen
.option tls_certificate main "string list&!!" unset
&<<SECTtlssni>>& will be re-expanded.
If this option is unset or empty a self-signed certificate will be
-.new
used.
Under Linux this is generated at daemon startup; on other platforms it will be
generated fresh for every connection.
-.wen
.option tls_crl main string&!! unset
.cindex "TLS" "server certificate revocation list"
&<<SECTreqciphssl>>& and &<<SECTreqciphgnu>>&.
-.new
.option tls_resumption_hosts main "host list&!!" unset
.cindex TLS resumption
This option controls which connections to offer the TLS resumption feature.
See &<<SECTresumption>>& for details.
-.wen
.option tls_try_verify_hosts main "host list&!!" unset
provide data for a transport is: &%errors_to%&, &%headers_add%&,
&%headers_remove%&, &%transport%&.
-.new
The name of a router is limited to be &drivernamemax; ASCII characters long;
prior to Exim 4.95 names would be silently truncated at this length, but now
it is enforced.
-.wen
.option address_data routers string&!! unset
When a router runs, the strings are evaluated in order,
to create variables which are added to the set associated with
the address.
-.new
This is done immediately after all the preconditions, before the
evaluation of the &%address_data%& option.
-.wen
The variable is set with the expansion of the value.
The variables can be used by the router options
(not including any preconditions)
.scindex IIDgenoptra1 "generic options" "transport"
.scindex IIDgenoptra2 "options" "generic; for transports"
.scindex IIDgenoptra3 "transport" "generic options for"
-.new
The name of a transport is limited to be &drivernamemax; ASCII characters long;
prior to Exim 4.95 names would be silently truncated at this length, but now
it is enforced.
-.wen
The following generic options apply to all transports:
its removal from incoming messages, so that delivered messages can safely be
resent to other recipients.
-.new
&*Note:*& If used on a transport handling multiple recipients
(the smtp transport unless &%rcpt_max%& is 1, the appendfile, pipe or lmtp
transport if &%batch_max%& is greater than 1)
then information about Bcc recipients will be leaked.
Doing so is generally not advised.
-.wen
.option event_action transports string&!! unset
delivery, it applies to the top level directory, not the maildir directories
beneath.
-.new
The option must be set to one of the words &"anywhere"&, &"inhome"&, or
&"belowhome"&, or to an absolute path.
-.wen
In the second and third cases, a home directory must have been
set for the transport, and the file or directory being created must
by an &(appendfile)& transport called &%address_file%&. See also
&%file_must_exist%&.
-.new
In the fourth case,
the value given for this option must be an absolute path for an
existing directory.
.cindex "tainted data" "de-tainting"
If "belowhome" checking is used, the file or directory path
becomes de-tainted.
-.wen
.option directory appendfile string&!! unset
(see &%maildir_format%& and &%mailstore_format%&), and see section
&<<SECTopdir>>& for further details of this form of delivery.
-.new
The result of expansion must not be tainted, unless the &%create_file%& option
specifies a path.
-.wen
.option directory_file appendfile string&!! "see below"
&%use_fcntl_lock%&, &%use_flock_lock%&, or &%use_lockfile%& must be set with
&%file%&.
-.new
The result of expansion must not be tainted, unless the &%create_file%& option
specifies a path.
-.wen
.cindex "NFS" "lock file"
.cindex "locking files"
TLS session for any host that matches this list.
&%tls_verify_certificates%& should also be set for the transport.
-.new
.option hosts_require_alpn smtp "host list&!!" unset
.cindex ALPN "require negotiation in client"
.cindex TLS ALPN
&*Note*&: prevention of fallback to in-clear connection is not
managed by this option; see &%hosts_require_tls%&.
-.wen
.option hosts_require_dane smtp "host list&!!" unset
.cindex DANE "transport options"
This option provides a list of servers to which, provided they announce
authentication support, Exim will attempt to authenticate as a client when it
connects. If authentication fails
-.new
and &%hosts_require_auth%& permits,
-.wen
Exim will try to transfer the message unauthenticated.
See also chapter &<<CHAPSMTPAUTH>>& for details of authentication.
.option hosts_try_dane smtp "host list&!!" *
.cindex DANE "transport options"
.cindex DANE "attempting for certain servers"
-.new
If built with DANE support, Exim will look up a
TLSA record for any host matching the list,
If one is found and that lookup was DNSSEC-validated,
then Exim requires that a DANE-verified TLS connection is made for that host;
there will be no fallback to in-clear communication.
-.wen
See the &%dnssec_request_domains%& router and transport options.
See section &<<SECDANE>>&.
permits this. A value setting of zero disables the limit.
-.new
.option message_linelength_limit smtp integer 998
.cindex "line length" limit
This option sets the maximum line length, in bytes, that the transport
It is generally wise to also check in the data ACL so that messages
received via SMTP can be refused without producing a bounce.
-.wen
.option multi_domain smtp boolean&!! true
&$address_data$&, &$domain_data$&, &$local_part_data$&,
&$host$&, &$host_address$& and &$host_port$&.
-.new
If the connection is DANE-enabled then this option is ignored;
only messages having the domain used for the DANE TLSA lookup are
sent on the connection.
-.wen
.option port smtp string&!! "see below"
.cindex "port" "sending TCP/IP"
transport. For details see section &<<SECTproxySOCKS>>&.
-.new
.option tls_alpn smtp string&!! unset
.cindex TLS "Application Layer Protocol Names"
.cindex TLS ALPN
As of writing no value has been standardised for email use.
The authors suggest using &"smtp"&.
-.wen
ciphers is a preference order.
-.new
.option tls_resumption_hosts smtp "host list&!!" unset
.cindex TLS resumption
This option controls which connections to use the TLS resumption feature.
See &<<SECTresumption>>& for details.
-.wen
.cindex SNI "setting in client"
.vindex "&$tls_sni$&"
If this option is set
-.new
and the connection is not DANE-validated
-.wen
then it sets the $tls_out_sni variable and causes any
TLS session to pass this value as the Server Name Indication extension to
the remote side, which can be used by the remote side to select an appropriate
transfer of mail between servers that have no managerial connection with each
other.
-.new
The name of an authenticator is limited to be &drivernamemax; ASCII characters long;
prior to Exim 4.95 names would be silently truncated at this length, but now
it is enforced.
-.wen
.cindex "AUTH" "description of"
.cindex "ESMTP extensions" AUTH
.endd
The lack of colons means that the entire text is sent with the AUTH
command, with the circumflex characters converted to NULs.
-.new
Note that due to the ambiguity of parsing three consectutive circumflex characters
there is no way to provide a password having a leading circumflex.
-.wen
A similar example
The macro _HAVE_AUTH_GSASL_SCRAM_SHA_256 will be defined
when this happens.
-.new
To see the list of mechanisms supported by the library run Exim with "auth" debug
enabled and look for a line containing "GNU SASL supports".
Note however that some may not have been tested from Exim.
-.wen
.option client_authz gsasl string&!! unset
.option client_spassword gsasl string&!! unset
-.new
This option is only supported for library versions 1.9.1 and greater.
The macro _HAVE_AUTH_GSASL_SCRAM_S_KEY will be defined when this is so.
-.wen
If a SCRAM mechanism is being used and this option is set
and correctly sized
Note that this value will depend on the salt and iteration-count
supplied by the server.
The option is expanded before use.
-.new
During the expansion &$auth1$& is set with the client username,
&$auth2$& with the iteration count, and
&$auth3$& with the salt.
plus the calculated salted password value value in &$auth4$&,
during the expansion of the &%client_set_id%& option.
A side-effect of this expansion can be used to prime the cache.
-.wen
.option server_channelbinding gsasl boolean false
. Do not plan to rely upon this feature for security, ever, without consulting
. with a subject matter expert (a cryptographic engineer).
-.new
This option was deprecated in previous releases due to doubts over
the "Triple Handshake" vulnerability.
Exim takes suitable precausions (requiring Extended Master Secret if TLS
Session Resumption was used) for safety.
-.wen
.option server_hostname gsasl string&!! "see below"
This should be documented with the feature. If the documentation does not
explicitly state that the feature is infeasible in the other TLS
implementation, then patches are welcome.
-.new
.next
The output from "exim -bV" will show which (if any) support was included
in the build.
Also, the macro "_HAVE_OPENSSL" or "_HAVE_GNUTLS" will be defined.
-.wen
.endlist
.endd
-.new
.section "Caching of static server configuration items" "SECTserverTLScache"
.cindex certificate caching
.cindex privatekey caching
Caching of the system Certificate Authorities bundle can
save siginificant time and processing on every TLS connection
accepted by Exim.
-.wen
The &%tls_verify_cert_hostnames%& option lists hosts for which additional
name checks are made on the server certificate.
-.new
The match against this list is, as per other Exim usage, the
IP for the host. That is most closely associated with the
name on the DNS A (or AAAA) record for the host.
However, the name that needs to be in the certificate
is the one at the head of any CNAME chain leading to the A record.
-.wen
The option defaults to always checking.
The &(smtp)& transport has two OCSP-related options:
-.new
.section "Caching of static client configuration items" "SECTclientTLScache"
.cindex certificate caching
.cindex privatekey caching
Caching of the system Certificate Authorities bundle can
save siginificant time and processing on every TLS connection
initiated by Exim.
-.wen
only point of caution. The &$tls_out_sni$& variable will be set to this string
for the lifetime of the client connection (including during authentication).
-.new
If DANE validated the connection attempt then the value of the &%tls_sni%& option
is forced to the domain part of the recipient address.
-.wen
Except during SMTP client sessions, if &$tls_in_sni$& is set then it is a string
received from a client.
0.5.10. (Its presence predates the current API which Exim uses, so if Exim
built, then you have SNI support).
-.new
.cindex TLS ALPN
.cindex ALPN "general information"
.cindex TLS "Application Layer Protocol Names"
This feature is available when Exim is built with
OpenSSL 1.1.0 or later or GnuTLS 3.2.0 or later;
the macro _HAVE_TLS_ALPN will be defined when this is so.
-.wen
.ecindex IIDencsmtp2
-.new
.section "TLS Resumption" "SECTresumption"
.cindex TLS resumption
TLS Session Resumption for TLS 1.2 and TLS 1.3 connections can be used (defined
.endlist
.endlist
-.wen
.section DANE "SECDANE"
response.
.vindex "&$acl_verify_message$&"
-.new
While the text is being expanded, the &$acl_verify_message$& variable
contains any message previously set.
Afterwards, &$acl_verify_message$& is cleared.
-.wen
If &%message%& is used on a statement that verifies an address, the message
specified overrides any message that is generated by the verification process.
different values. Some DNS lists may return more than one address record;
see section &<<SECThanmuldnsrec>>& for details of how they are checked.
-.new
Values returned by a properly running DBSBL should be in the 127.0.0.0/8
range. If a DNSBL operator loses control of the domain, lookups on it
may start returning other addresses. Because of this, Exim now ignores
returned values outside the 127/8 region.
-.wen
.section "Variables set from DNS lists" "SECID204"
immediately after a successful redirection. By default, if a redirection
generates just one address, that address is also verified. See further
discussion in section &<<SECTredirwhilveri>>&.
-.new
.next
If the &%quota%& option is specified for recipient verify,
successful routing to an appendfile transport is followed by a call into
No actual delivery is done, but verification will succeed if the quota
is sufficient for the message (if the sender gave a message size) or
not already exceeded (otherwise).
-.wen
.endlist
.cindex "verifying address" "differentiating failures"
&%recipient%&: The RCPT command in a callout was rejected.
.next
&%postmaster%&: The postmaster check in a callout was rejected.
-.new
.next
&%quota%&: The quota check for a local recipient did non pass.
.endlist
-.new
.section "Quota caching" "SECTquotacache"
.cindex "hints database" "quota cache"
.cindex "quota" "cache, description of"
.vitem &*no_cache*&
Set both positive and negative lifetimes to zero.
-.wen
.section "Sender address verification reporting" "SECTsenaddver"
.cindex "verifying" "suppressing error details"
SMTP RCPT commands in one transaction) the second and subsequent addresses are
flagged with &`->`& instead of &`=>`&. When two or more messages are delivered
down a single SMTP connection, an asterisk follows the
-.new
remote IP address (and port if enabled)
-.wen
in the log lines for the second and subsequent messages.
When two or more messages are delivered down a single TLS connection, the
DNS and some TLS-related information logged for the first message delivered
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
-.new
&"=>"&, &"->"&, &"=="& and &"**"& lines.
-.wen
The latter can be disabled by turning off the &%outgoing_interface%& option.
.next
.cindex log "incoming proxy address"
.next
.cindex "log" "TLS resumption"
.cindex "TLS" "logging session resumption"
-.new
&%tls_resumption%&: When a message is sent or received over an encrypted
connection and the TLS session resumed one used on a previous TCP connection,
an asterisk is appended to the X= cipher field in the log line.
-.wen
.next
.cindex "log" "TLS SNI"
.cindex "TLS" "logging SNI"
.next
&'ratelimit'&: the data for implementing the ratelimit ACL condition
.next
-.new
&'tls'&: TLS session resumption data
-.wen
.next
&'misc'&: other hints data
.endlist
If the option is empty after expansion, DKIM signing is not done for this domain,
and no error will result even if &%dkim_strict%& is set.
-.new
To do, for example, dual-signing with RSA and EC keys
this could be be used:
.code
dkim_selector = ec_sel : rsa_sel
dkim_private_key = KEYS_DIR/$dkim_selector
.endd
-.wen
.option dkim_private_key smtp string&!! unset
This sets the private key to use.
.section "SRS (Sender Rewriting Scheme)" SECTSRS
.cindex SRS "sender rewriting scheme"
-.new
SRS can be used to modify sender addresses when forwarding so that
SPF verification does not object to them.
It operates by encoding the original envelope sender in a new
.endd
-.wen
git://git.exim.org / exim.git / commitdiff