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An Example configuration file taken from a defualt installation of Red Hat Enterprise Linux or CentOS. This file is similar to the one you would find in the /etc/exim/ directory on a server running exim v4.43.
######################################################################
# Runtime configuration file for Exim #
######################################################################
# This is a default configuration file which will operate correctly in
# uncomplicated installations. Please see the manual for a complete list
# of all the runtime configuration options that can be included in a
# configuration file. There are many more than are mentioned here. The
# manual is in the file doc/spec.txt in the Exim distribution as a plain
# ASCII file. Other formats (PostScript, Texinfo, HTML, PDF) are available
# from the Exim ftp sites. The manual is also online at the Exim web sites.
# This file is divided into several parts, all but the first of which are
# headed by a line starting with the word "begin". Only those parts that
# are required need to be present. Blank lines, and lines starting with #
# are ignored.
########### IMPORTANT ########## IMPORTANT ########### IMPORTANT ###########
# #
# Whenever you change Exim's configuration file, you *must* remember to #
# HUP the Exim daemon, because it will not pick up the new configuration #
# until you do. However, any other Exim processes that are started, for #
# example, a process started by an MUA in order to send a message, will #
# see the new configuration as soon as it is in place. #
# #
# You do not need to HUP the daemon for changes in auxiliary files that #
# are referenced from this file. They are read every time they are used. #
# #
# It is usually a good idea to test a new configuration for syntactic #
# correctness before installing it (for example, by running the command #
# "exim -C /config/file.new -bV"). #
# #
########### IMPORTANT ########## IMPORTANT ########### IMPORTANT ###########
######################################################################
# MAIN CONFIGURATION SETTINGS #
######################################################################
# Specify your host's canonical name here. This should normally be the fully
# qualified "official" name of your host. If this option is not set, the
# uname() function is called to obtain the name. In many cases this does
# the right thing and you need not set anything explicitly.
# primary_hostname =
# The next three settings create two lists of domains and one list of hosts.
# These lists are referred to later in this configuration using the syntax
# +local_domains, +relay_to_domains, and +relay_from_hosts, respectively. They
# are all colon-separated lists:
domainlist local_domains = @
domainlist relay_to_domains =
hostlist relay_from_hosts = 127.0.0.1
# Most straightforward access control requirements can be obtained by
# appropriate settings of the above options. In more complicated situations, you
# may need to modify the Access Control List (ACL) which appears later in this
# file.
# The first setting specifies your local domains, for example:
#
# domainlist local_domains = my.first.domain : my.second.domain
#
# You can use "@" to mean "the name of the local host", as in the default
# setting above. This is the name that is specified by primary_hostname,
# as specified above (or defaulted). If you do not want to do any local
# deliveries, remove the "@" from the setting above. If you want to accept mail
# addressed to your host's literal IP address, for example, mail addressed to
# "user@[192.168.23.44]", you can add "@[]" as an item in the local domains
# list. You also need to uncomment "allow_domain_literals" below. This is not
# recommended for today's Internet.
# The second setting specifies domains for which your host is an incoming relay.
# If you are not doing any relaying, you should leave the list empty. However,
# if your host is an MX backup or gateway of some kind for some domains, you
# must set relay_to_domains to match those domains. For example:
#
# domainlist relay_to_domains = *.myco.com : my.friend.org
#
# This will allow any host to relay through your host to those domains.
# See the section of the manual entitled "Control of relaying" for more
# information.
# The third setting specifies hosts that can use your host as an outgoing relay
# to any other host on the Internet. Such a setting commonly refers to a
# complete local network as well as the localhost. For example:
#
# hostlist relay_from_hosts = 127.0.0.1 : 192.168.0.0/16
#
# The "/16" is a bit mask (CIDR notation), not a number of hosts. Note that you
# have to include 127.0.0.1 if you want to allow processes on your host to send
# SMTP mail by using the loopback address. A number of MUAs use this method of
# sending mail.
# All three of these lists may contain many different kinds of item, including
# wildcarded names, regular expressions, and file lookups. See the reference
# manual for details. The lists above are used in the access control list for
# incoming messages. The name of this ACL is defined here:
acl_smtp_rcpt = acl_check_rcpt
# You should not change that setting until you understand how ACLs work.
# The following ACL entries are used if you want to do content scanning with
# the exiscan-acl patch. When you uncomment one of these lines, you must also
# review the respective entries in the ACL section further below.
# acl_smtp_mime = acl_check_mime
# acl_smtp_data = acl_check_content
# This configuration variable defines the virus scanner that is used with
# the 'malware' ACL condition of the exiscan acl-patch. If you do not use
# virus scanning, leave it commented. Please read doc/exiscan-acl-readme.txt
# for a list of supported scanners.
# av_scanner = sophie:/var/run/sophie
# The following setting is only needed if you use the 'spam' ACL condition
# of the exiscan-acl patch. It specifies on which host and port the SpamAssassin
# "spamd" daemon is listening. If you do not use this condition, or you use
# the default of "127.0.0.1 783", you can omit this option.
# spamd_address = 127.0.0.1 783
# Specify the domain you want to be added to all unqualified addresses
# here. An unqualified address is one that does not contain an "@" character
# followed by a domain. For example, "
This e-mail address is being protected from spam bots, you need JavaScript enabled to view it
" is a fully qualified
# address, but the string "caesar" (i.e. just a login name) is an unqualified
# email address. Unqualified addresses are accepted only from local callers by
# default. See the recipient_unqualified_hosts option if you want to permit
# unqualified addresses from remote sources. If this option is not set, the
# primary_hostname value is used for qualification.
# qualify_domain =
# If you want unqualified recipient addresses to be qualified with a different
# domain to unqualified sender addresses, specify the recipient domain here.
# If this option is not set, the qualify_domain value is used.
# qualify_recipient =
# The following line must be uncommented if you want Exim to recognize
# addresses of the form "user@[10.11.12.13]" that is, with a "domain literal"
# (an IP address) instead of a named domain. The RFCs still require this form,
# but it makes little sense to permit mail to be sent to specific hosts by
# their IP address in the modern Internet. This ancient format has been used
# by those seeking to abuse hosts by using them for unwanted relaying. If you
# really do want to support domain literals, uncomment the following line, and
# see also the "domain_literal" router below.
# allow_domain_literals
# No deliveries will ever be run under the uids of these users (a colon-
# separated list). An attempt to do so causes a panic error to be logged, and
# the delivery to be deferred. This is a paranoic safety catch. There is an
# even stronger safety catch in the form of the FIXED_NEVER_USERS setting
# in the configuration for building Exim. The list of users that it specifies
# is built into the binary, and cannot be changed. The option below just adds
# additional users to the list. The default for FIXED_NEVER_USERS is "root",
# but just to be absolutely sure, the default here is also "root".
# Note that the default setting means you cannot deliver mail addressed to root
# as if it were a normal user. This isn't usually a problem, as most sites have
# an alias for root that redirects such mail to a human administrator.
never_users = root
# The setting below causes Exim to do a reverse DNS lookup on all incoming
# IP calls, in order to get the true host name. If you feel this is too
# expensive, you can specify the networks for which a lookup is done, or
# remove the setting entirely.
host_lookup = *
# The settings below, which are actually the same as the defaults in the
# code, cause Exim to make RFC 1413 (ident) callbacks for all incoming SMTP
# calls. You can limit the hosts to which these calls are made, and/or change
# the timeout that is used. If you set the timeout to zero, all RFC 1413 calls
# are disabled. RFC 1413 calls are cheap and can provide useful information
# for tracing problem messages, but some hosts and firewalls have problems
# with them. This can result in a timeout instead of an immediate refused
# connection, leading to delays on starting up an SMTP session.
rfc1413_hosts = *
rfc1413_query_timeout = 30s
# By default, Exim expects all envelope addresses to be fully qualified, that
# is, they must contain both a local part and a domain. If you want to accept
# unqualified addresses (just a local part) from certain hosts, you can specify
# these hosts by setting one or both of
#
# sender_unqualified_hosts =
# recipient_unqualified_hosts =
#
# to control sender and recipient addresses, respectively. When this is done,
# unqualified addresses are qualified using the settings of qualify_domain
# and/or qualify_recipient (see above).
# If you want Exim to support the "percent hack" for certain domains,
# uncomment the following line and provide a list of domains. The "percent
# hack" is the feature by which mail addressed to x%y@z (where z is one of
# the domains listed) is locally rerouted to x@y and sent on. If z is not one
# of the "percent hack" domains, x%y is treated as an ordinary local part. This
# hack is rarely needed nowadays; you should not enable it unless you are sure
# that you really need it.
#
# percent_hack_domains =
#
# As well as setting this option you will also need to remove the test
# for local parts containing % in the ACL definition below.
# When Exim can neither deliver a message nor return it to sender, it "freezes"
# the delivery error message (aka "bounce message"). There are also other
# circumstances in which messages get frozen. They will stay on the queue for
# ever unless one of the following options is set.
# This option unfreezes frozen bounce messages after two days, tries
# once more to deliver them, and ignores any delivery failures.
ignore_bounce_errors_after = 2d
# This option cancels (removes) frozen messages that are older than a week.
timeout_frozen_after = 7d
######################################################################
# ACL CONFIGURATION #
# Specifies access control lists for incoming SMTP mail #
######################################################################
begin acl
# This access control list is used for every RCPT command in an incoming
# SMTP message. The tests are run in order until the address is either
# accepted or denied.
acl_check_rcpt:
# Accept if the source is local SMTP (i.e. not over TCP/IP). We do this by
# testing for an empty sending host field.
accept hosts = :
#############################################################################
# The following section of the ACL is concerned with local parts that contain
# @ or % or ! or / or | or dots in unusual places.
#
# The characters other than dots are rarely found in genuine local parts, but
# are often tried by people looking to circumvent relaying restrictions.
# Therefore, although they are valid in local parts, these rules lock them
# out, as a precaution.
#
# Empty components (two dots in a row) are not valid in RFC 2822, but Exim
# allows them because they have been encountered. (Consider local parts
# constructed as "firstinitial.secondinitial.familyname" when applied to
# someone like me, who has no second initial.) However, a local part starting
# with a dot or containing /../ can cause trouble if it is used as part of a
# file name (e.g. for a mailing list). This is also true for local parts that
# contain slashes. A pipe symbol can also be troublesome if the local part is
# incorporated unthinkingly into a shell command line.
#
# Two different rules are used. The first one is stricter, and is applied to
# messages that are addressed to one of the local domains handled by this
# host. It blocks local parts that begin with a dot or contain @ % ! / or |.
# If you have local accounts that include these characters, you will have to
# modify this rule.
deny message = Restricted characters in address
domains = +local_domains
local_parts = ^[.] : ^.*[@%!/|]
# The second rule applies to all other domains, and is less strict. This
# allows your own users to send outgoing messages to sites that use slashes
# and vertical bars in their local parts. It blocks local parts that begin
# with a dot, slash, or vertical bar, but allows these characters within the
# local part. However, the sequence /../ is barred. The use of @ % and ! is
# blocked, as before. The motivation here is to prevent your users (or
# your users' viruses) from mounting certain kinds of attack on remote sites.
deny message = Restricted characters in address
domains = !+local_domains
local_parts = ^[./|] : ^.*[@%!] : ^.*/\\.\\./
#############################################################################
# Accept mail to postmaster in any local domain, regardless of the source,
# and without verifying the sender.
accept local_parts = postmaster
domains = +local_domains
# Deny unless the sender address can be verified.
require verify = sender
#############################################################################
# There are no checks on DNS "black" lists because the domains that contain
# these lists are changing all the time. However, here are two examples of
# how you could get Exim to perform a DNS black list lookup at this point.
# The first one denies, while the second just warns.
#
# deny message = rejected because $sender_host_address is in a black list at $dnslist_domain\n$dnslist_text
# dnslists = black.list.example
#
# warn message = X-Warning: $sender_host_address is in a black list at $dnslist_domain
# log_message = found in $dnslist_domain
# dnslists = black.list.example
#############################################################################
# Accept if the address is in a local domain, but only if the recipient can
# be verified. Otherwise deny. The "endpass" line is the border between
# passing on to the next ACL statement (if tests above it fail) or denying
# access (if tests below it fail).
accept domains = +local_domains
endpass
verify = recipient
# Accept if the address is in a domain for which we are relaying, but again,
# only if the recipient can be verified.
accept domains = +relay_to_domains
endpass
verify = recipient
# If control reaches this point, the domain is neither in +local_domains
# nor in +relay_to_domains.
# Accept if the message comes from one of the hosts for which we are an
# outgoing relay. Recipient verification is omitted here, because in many
# cases the clients are dumb MUAs that don't cope well with SMTP error
# responses. If you are actually relaying out from MTAs, you should probably
# add recipient verification here.
accept hosts = +relay_from_hosts
# Accept if the message arrived over an authenticated connection, from
# any host. Again, these messages are usually from MUAs, so recipient
# verification is omitted.
accept authenticated = *
# Reaching the end of the ACL causes a "deny", but we might as well give
# an explicit message.
deny message = relay not permitted
# These access control lists are used for content scanning with the exiscan-acl
# patch. You must also uncomment the entries for acl_smtp_data and acl_smtp_mime
# (scroll up), otherwise the ACLs will not be used. IMPORTANT: the default entries here
# should be treated as EXAMPLES. You MUST read the file doc/exiscan-acl-spec.txt
# to fully understand what you are doing ...
acl_check_mime:
# Decode MIME parts to disk. This will support virus scanners later.
warn decode = default
# File extension filtering.
deny message = Blacklisted file extension detected
condition = ${if match \
{${lc:$mime_filename}} \
{\N(\.exe|\.pif|\.bat|\.scr|\.lnk|\.com)$\N} \
{1}{0}}
# Reject messages that carry chinese character sets.
# WARNING: This is an EXAMPLE.
deny message = Sorry, noone speaks chinese here
condition = ${if eq{$mime_charset}{gb2312}{1}{0}}
accept
acl_check_content:
# Reject virus infested messages.
deny message = This message contains malware ($malware_name)
malware = *
# Always add X-Spam-Score and X-Spam-Report headers, using SA system-wide settings
# (user "nobody"), no matter if over threshold or not.
warn message = X-Spam-Score: $spam_score ($spam_bar)
spam = nobody:true
warn message = X-Spam-Report: $spam_report
spam = nobody:true
# Add X-Spam-Flag if spam is over system-wide threshold
warn message = X-Spam-Flag: YES
spam = nobody
# Reject spam messages with score over 10, using an extra condition.
deny message = This message scored $spam_score points. Congratulations!
spam = nobody:true
condition = ${if >{$spam_score_int}{100}{1}{0}}
# finally accept all the rest
accept
######################################################################
# ROUTERS CONFIGURATION #
# Specifies how addresses are handled #
######################################################################
# THE ORDER IN WHICH THE ROUTERS ARE DEFINED IS IMPORTANT! #
# An address is passed to each router in turn until it is accepted. #
######################################################################
begin routers
# This router routes to remote hosts over SMTP by explicit IP address,
# when an email address is given in "domain literal" form, for example,
# <user@[192.168.35.64]>. The RFCs require this facility. However, it is
# little-known these days, and has been exploited by evil people seeking
# to abuse SMTP relays. Consequently it is commented out in the default
# configuration. If you uncomment this router, you also need to uncomment
# allow_domain_literals above, so that Exim can recognize the syntax of
# domain literal addresses.
# domain_literal:
# driver = ipliteral
# domains = ! +local_domains
# transport = remote_smtp
# This router routes addresses that are not in local domains by doing a DNS
# lookup on the domain name. Any domain that resolves to 0.0.0.0 or to a
# loopback interface address (127.0.0.0/8) is treated as if it had no DNS
# entry. Note that 0.0.0.0 is the same as 0.0.0.0/32, which is commonly treated
# as the local host inside the network stack. It is not 0.0.0.0/0, the default
# route. If the DNS lookup fails, no further routers are tried because of
# the no_more setting, and consequently the address is unrouteable.
dnslookup:
driver = dnslookup
domains = ! +local_domains
transport = remote_smtp
ignore_target_hosts = 0.0.0.0 : 127.0.0.0/8
no_more
# The remaining routers handle addresses in the local domain(s).
# This router handles aliasing using a linearly searched alias file with the
# name SYSTEM_ALIASES_FILE. When this configuration is installed automatically,
# the name gets inserted into this file from whatever is set in Exim's
# build-time configuration. The default path is the traditional /etc/aliases.
# If you install this configuration by hand, you need to specify the correct
# path in the "data" setting below.
#
##### NB You must ensure that the alias file exists. It used to be the case
##### NB that every Unix had that file, because it was the Sendmail default.
##### NB These days, there are systems that don't have it. Your aliases
##### NB file should at least contain an alias for "postmaster".
#
# If any of your aliases expand to pipes or files, you will need to set
# up a user and a group for these deliveries to run under. You can do
# this by uncommenting the "user" option below (changing the user name
# as appropriate) and adding a "group" option if necessary. Alternatively, you
# can specify "user" on the transports that are used. Note that the transports
# listed below are the same as are used for .forward files; you might want
# to set up different ones for pipe and file deliveries from aliases.
system_aliases:
driver = redirect
allow_fail
allow_defer
data = ${lookup{$local_part}lsearch{/etc/aliases}}
# user = exim
file_transport = address_file
pipe_transport = address_pipe
# This router handles forwarding using traditional .forward files in users'
# home directories. If you want it also to allow mail filtering when a forward
# file starts with the string "# Exim filter" or "# Sieve filter", uncomment
# the "allow_filter" option.
# If you want this router to treat local parts with suffixes introduced by "-"
# or "+" characters as if the suffixes did not exist, uncomment the two local_
# part_suffix options. Then, for example,
This e-mail address is being protected from spam bots, you need JavaScript enabled to view it
will be treated
# in the same way as
This e-mail address is being protected from spam bots, you need JavaScript enabled to view it
by this router. You probably want to make
# the same change to the localuser router.
# The no_verify setting means that this router is skipped when Exim is
# verifying addresses. Similarly, no_expn means that this router is skipped if
# Exim is processing an EXPN command.
# The check_ancestor option means that if the forward file generates an
# address that is an ancestor of the current one, the current one gets
# passed on instead. This covers the case where A is aliased to B and B
# has a .forward file pointing to A.
# The three transports specified at the end are those that are used when
# forwarding generates a direct delivery to a file, or to a pipe, or sets
# up an auto-reply, respectively.
userforward:
driver = redirect
check_local_user
# local_part_suffix = +* : -*
# local_part_suffix_optional
file = $home/.forward
# allow_filter
no_verify
no_expn
check_ancestor
file_transport = address_file
pipe_transport = address_pipe
reply_transport = address_reply
# This router matches local user mailboxes. If the router fails, the error
# message is "Unknown user".
# If you want this router to treat local parts with suffixes introduced by "-"
# or "+" characters as if the suffixes did not exist, uncomment the two local_
# part_suffix options. Then, for example,
This e-mail address is being protected from spam bots, you need JavaScript enabled to view it
will be treated
# in the same way as
This e-mail address is being protected from spam bots, you need JavaScript enabled to view it
by this router.
localuser:
driver = accept
check_local_user
# local_part_suffix = +* : -*
# local_part_suffix_optional
transport = local_delivery
cannot_route_message = Unknown user
######################################################################
# TRANSPORTS CONFIGURATION #
######################################################################
# ORDER DOES NOT MATTER #
# Only one appropriate transport is called for each delivery. #
######################################################################
# A transport is used only when referenced from a router that successfully
# handles an address.
begin transports
# This transport is used for delivering messages over SMTP connections.
remote_smtp:
driver = smtp
# This transport is used for local delivery to user mailboxes in traditional
# BSD mailbox format. By default it will be run under the uid and gid of the
# local user, and requires the sticky bit to be set on the /var/mail directory.
# Some systems use the alternative approach of running mail deliveries under a
# particular group instead of using the sticky bit. The commented options below
# show how this can be done.
local_delivery:
driver = appendfile
file = /var/mail/$local_part
delivery_date_add
envelope_to_add
return_path_add
group = mail
mode = 0660
# This transport is used for handling pipe deliveries generated by alias or
# .forward files. If the pipe generates any standard output, it is returned
# to the sender of the message as a delivery error. Set return_fail_output
# instead of return_output if you want this to happen only when the pipe fails
# to complete normally. You can set different transports for aliases and
# forwards if you want to - see the references to address_pipe in the routers
# section above.
address_pipe:
driver = pipe
return_output
# This transport is used for handling deliveries directly to files that are
# generated by aliasing or forwarding.
address_file:
driver = appendfile
delivery_date_add
envelope_to_add
return_path_add
# This transport is used for handling autoreplies generated by the filtering
# option of the userforward router.
address_reply:
driver = autoreply
# This transport is used to deliver local mail to cyrus IMAP server via UNIX
# socket.
#
#local_delivery:
# driver = lmtp
# command = "/usr/lib/cyrus-imapd/deliver -l"
# batch_max = 20
# user = cyrus
######################################################################
# RETRY CONFIGURATION #
######################################################################
begin retry
# This single retry rule applies to all domains and all errors. It specifies
# retries every 15 minutes for 2 hours, then increasing retry intervals,
# starting at 1 hour and increasing each time by a factor of 1.5, up to 16
# hours, then retries every 6 hours until 4 days have passed since the first
# failed delivery.
# Address or Domain Error Retries
# ----------------- ----- -------
* * F,2h,15m; G,16h,1h,1.5; F,4d,6h
######################################################################
# REWRITE CONFIGURATION #
######################################################################
# There are no rewriting specifications in this default configuration file.
begin rewrite
######################################################################
# AUTHENTICATION CONFIGURATION #
######################################################################
# There are no authenticator specifications in this default configuration file.
begin authenticators
######################################################################
# CONFIGURATION FOR local_scan() #
######################################################################
# If you have built Exim to include a local_scan() function that contains
# tables for private options, you can define those options here. Remember to
# uncomment the "begin" line. It is commented by default because it provokes
# an error with Exim binaries that are not built with LOCAL_SCAN_HAS_OPTIONS
# set in the Local/Makefile.
# begin local_scan
# End of Exim configuration file
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