######################################################################
# 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
# manual for details. The lists above are used in the access control lists for
# checking incoming messages. The names of these ACLs are defined here:
-acl_smtp_rcpt = acl_check_rcpt
-acl_smtp_data = acl_check_data
+acl_smtp_rcpt = acl_check_rcpt
+acl_smtp_data_prdr = acl_check_prdr
+acl_smtp_data = acl_check_data
# You should not change those settings until you understand how ACLs work.
# tls_certificate = /etc/ssl/exim.crt
# tls_privatekey = /etc/ssl/exim.pem
+# For OpenSSL, prefer EC- over RSA-authenticated ciphers
+# tls_require_ciphers = ECDSA:RSA:!COMPLEMENTOFDEFAULT
+
# In order to support roaming users who wish to send email from anywhere,
# you may want to make Exim listen on other ports as well as port 25, in
# case these users need to send email from a network that blocks port 25.
host_lookup = *
+# The setting below causes Exim to try to initialize the system resolver
+# library with DNSSEC support. It has no effect if your library lacks
+# DNSSEC support.
+
+dns_dnssec_ok = 1
+
+
# The settings below 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
# accept_8bitmime = false
+# Exim does not make use of environment variables itself. However,
+# libraries that Exim uses (e.g. LDAP) depend on specific environment settings.
+# There are two lists: keep_environment for the variables we trust, and
+# add_environment for variables we want to set to a specific value.
+# Note that TZ is handled separately by the timezone runtime option
+# and TIMEZONE_DEFAULT buildtime option.
+
+# keep_environment = ^LDAP
+# add_environment = PATH=/usr/bin::/bin
+
+
+
######################################################################
# ACL CONFIGURATION #
# Specifies access control lists for incoming SMTP mail #
control = submission
control = dkim_disable_verify
+ # Insist that a HELO/EHLO was accepted.
+
+ require message = nice hosts say HELO first
+ condition = ${if def:sender_helo_name}
+
# Insist that any other recipient address that we accept is either in one of
# our local domains, or is in a domain for which we explicitly allow
# relaying. Any other domain is rejected as being unacceptable for relaying.
# require verify = csa
#############################################################################
+ #############################################################################
+ # If doing per-user content filtering then recipients with filters different
+ # to the first recipient must be deferred unless the sender talks PRDR.
+ #
+ # defer !condition = $prdr_requested
+ # condition = ${if > {0}{$receipients_count}}
+ # condition = ${if !eq {$acl_m_content_filter} \
+ # {${lookup PER_RCPT_CONTENT_FILTER}}}
+ # warn !condition = $prdr_requested
+ # condition = ${if > {0}{$receipients_count}}
+ # set acl_m_content_filter = ${lookup PER_RCPT_CONTENT_FILTER}
+ #############################################################################
+
# At this point, the address has passed all the checks that have been
# configured, so we accept it unconditionally.
accept
+# This ACL is used once per recipient, for multi-recipient messages, if
+# we advertised PRDR. It can be used to perform receipient-dependent
+# header- and body- based filtering and rejections.
+# We set a variable to record that PRDR was active used, so that checking
+# in the data ACL can be skipped.
+
+acl_check_prdr:
+ warn set acl_m_did_prdr = y
+
+ #############################################################################
+ # do lookup on filtering, with $local_part@$domain, deny on filter match
+ #
+ # deny set acl_m_content_filter = ${lookup PER_RCPT_CONTENT_FILTER}
+ # condition = ...
+ #############################################################################
+
+ accept
+
# This ACL is used after the contents of a message have been received. This
# is the ACL in which you can test a message's headers or body, and in
# particular, this is where you can invoke external virus or spam scanners.
acl_check_data:
+ # Deny if the message contains an overlong line. Per the standards
+ # we should never receive one such via SMTP.
+ #
+ deny message = maximum allowed line length is 998 octets, \
+ got $max_received_linelength
+ condition = ${if > {$max_received_linelength}{998}}
+
+ # Deny if the headers contain badly-formed addresses.
+ #
+ deny !verify = header_syntax
+ message = header syntax
+ log_message = header syntax ($acl_verify_message)
+
# Deny if the message contains a virus. Before enabling this check, you
# must install a virus scanner and set the av_scanner option above.
#
# X-Spam_bar: $spam_bar\n\
# X-Spam_report: $spam_report
+ #############################################################################
+ # No more tests if PRDR was actively used.
+ # accept condition = ${if def:acl_m_did_prdr}
+ #
+ # To get here, all message recipients must have identical per-user
+ # content filtering (enforced by RCPT ACL). Do lookup for filter
+ # and deny on match.
+ #
+ # deny set acl_m_content_filter = ${lookup PER_RCPT_CONTENT_FILTER}
+ # condition = ...
+ #############################################################################
+
+
# Accept the message.
accept
ignore_target_hosts = 0.0.0.0 : 127.0.0.0/8
# if ipv6-enabled then instead use:
# ignore_target_hosts = <; 0.0.0.0 ; 127.0.0.0/8 ; ::1
+ dnssec_request_domains = *
no_more
# smarthost:
# driver = manualroute
# domains = ! +local_domains
-# transport = remote_smtp
+# transport = smarthost_smtp
# route_data = MAIL.HOSTNAME.FOR.CENTRAL.SERVER.EXAMPLE
# ignore_target_hosts = <; 0.0.0.0 ; 127.0.0.0/8 ; ::1
# no_more
# This transport is used for delivering messages over SMTP connections.
+# Refuse to send any message with over-long lines, which could have
+# been received other than via SMTP. The use of message_size_limit to
+# enforce this is a red herring.
remote_smtp:
driver = smtp
+ hosts_try_prdr = *
+ message_size_limit = ${if > {$max_received_linelength}{998} {1}{0}}
+.ifdef _HAVE_DANE
+ dnssec_request_domains = *
+ hosts_try_dane = *
+.endif
+
+
+# This transport is used for delivering messages to a smarthost, if the
+# smarthost router is enabled. This starts from the same basis as
+# "remote_smtp" but then turns on various security options, because
+# we assume that if you're told "use smarthost.example.org as the smarthost"
+# then there will be TLS available, with a verifiable certificate for that
+# hostname, using decent TLS.
+
+smarthost_smtp:
+ driver = smtp
+ hosts_try_prdr = *
+ message_size_limit = ${if > {$max_received_linelength}{998} {1}{0}}
+ multi_domain
+ #
+.ifdef _HAVE_TLS
+ # Comment out any of these which you have to, then file a Support
+ # request with your smarthost provider to get things fixed:
+ hosts_require_tls = *
+ tls_sni = $host
+ tls_verify_hosts = *
+ # As long as tls_verify_hosts is enabled, this won't matter, but if you
+ # have to comment it out then this will at least log whether you succeed
+ # or not:
+ tls_try_verify_hosts = *
+ #
+.ifdef _HAVE_OPENSSL
+ tls_require_ciphers = HIGH:!aNULL:@STRENGTH
+.endif
+.ifdef _HAVE_GNUTLS
+ tls_require_ciphers = SECURE192:-VERS-SSL3.0:-VERS-TLS1.0:-VERS-TLS1.1
+.endif
+.endif
# This transport is used for local delivery to user mailboxes in traditional
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