Postfix – Check Outgoing Mail for Spam

postfixspam

How can I force postfix to check (and log/flag/etc) all outgoing mail for spam?

Just want to make sure I'm doing my part on my servers.

EDIT: Postfix config, as requested.

main.cf

# See /usr/share/postfix/main.cf.dist for a commented, more complete version


# Debian specific:  Specifying a file name will cause the first
# line of that file to be used as the name.  The Debian default
# is /etc/mailname.
#myorigin = /etc/mailname

smtpd_banner = $myhostname ESMTP $mail_name (Debian/GNU)
biff = no

# appending .domain is the MUA's job.
append_dot_mydomain = no

# Uncomment the next line to generate "delayed mail" warnings
#delay_warning_time = 4h

readme_directory = no

# TLS parameters
smtpd_tls_cert_file=/etc/ssl/certs/ssl-cert-snakeoil.pem
smtpd_tls_key_file=/etc/ssl/private/ssl-cert-snakeoil.key
smtpd_use_tls=yes
smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache
smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache

smtpd_sasl_type = dovecot
smtpd_sasl_path = private/auth

smtpd_sasl_auth_enable = yes
smtpd_sasl_security_options = noanonymous
broken_sasl_auth_clients = yes

smtpd_recipient_restrictions =
   permit_sasl_authenticated,
   permit_mynetworks,
   reject_unauth_destination

# See /usr/share/doc/postfix/TLS_README.gz in the postfix-doc package for
# information on enabling SSL in the smtp client.

alias_maps = hash:/etc/aliases

myhostname = example.com
myorigin = /etc/mailname
mydestination = localhost, localhost.localdomain, localhost
relayhost =
mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128
mailbox_command = procmail -a "$EXTENSION"
mailbox_size_limit = 0
recipient_delimiter = +
inet_interfaces = all
content_filter = smtp-amavis:[127.0.0.1]:10024

transport_maps = mysql:/etc/postfix/mysql/transport_maps.cf

virtual_mailbox_domains = mysql:/etc/postfix/mysql/virtual_alias_domains.cf
virtual_alias_maps = mysql:/etc/postfix/mysql/virtual_alias_maps.cf


virtual_mailbox_base = /var/mail
virtual_mailbox_maps = mysql:/etc/postfix/mysql/virtual_mailbox_maps.cf
virtual_minimum_uid = 100
virtual_uid_maps = static:5000
virtual_gid_maps = static:5000
dovecot_destination_recipient_limit = 1

master.cf

#
# Postfix master process configuration file.  For details on the format
# of the file, see the master(5) manual page (command: "man 5 master").
#
# Do not forget to execute "postfix reload" after editing this file.
#
# ==========================================================================
# service type  private unpriv  chroot  wakeup  maxproc command + args
#               (yes)   (yes)   (yes)   (never) (100)
# ==========================================================================
smtp      inet  n       -       -       -       -       smtpd
submission inet n       -       -       -       -       smtpd
#  -o smtpd_tls_security_level=encrypt
#  -o smtpd_sasl_auth_enable=yes
#  -o smtpd_client_restrictions=permit_sasl_authenticated,reject
#  -o milter_macro_daemon_name=ORIGINATING
#smtps     inet  n       -       -       -       -       smtpd
#  -o smtpd_tls_wrappermode=yes
#  -o smtpd_sasl_auth_enable=yes
#  -o smtpd_client_restrictions=permit_sasl_authenticated,reject
#  -o milter_macro_daemon_name=ORIGINATING
#628      inet  n       -       -       -       -       qmqpd
pickup    fifo  n       -       -       60      1       pickup
cleanup   unix  n       -       -       -       0       cleanup
qmgr      fifo  n       -       n       300     1       qmgr
#qmgr     fifo  n       -       -       300     1       oqmgr
tlsmgr    unix  -       -       -       1000?   1       tlsmgr
rewrite   unix  -       -       -       -       -       trivial-rewrite
bounce    unix  -       -       -       -       0       bounce
defer     unix  -       -       -       -       0       bounce
trace     unix  -       -       -       -       0       bounce
verify    unix  -       -       -       -       1       verify
flush     unix  n       -       -       1000?   0       flush
proxymap  unix  -       -       n       -       -       proxymap
proxywrite unix -       -       n       -       1       proxymap
smtp      unix  -       -       -       -       -       smtp
# When relaying mail as backup MX, disable fallback_relay to avoid MX loops
relay     unix  -       -       -       -       -       smtp
    -o smtp_fallback_relay=
#       -o smtp_helo_timeout=5 -o smtp_connect_timeout=5
showq     unix  n       -       -       -       -       showq
error     unix  -       -       -       -       -       error
retry     unix  -       -       -       -       -       error
discard   unix  -       -       -       -       -       discard
local     unix  -       n       n       -       -       local
virtual   unix  -       n       n       -       -       virtual
lmtp      unix  -       -       -       -       -       lmtp
anvil     unix  -       -       -       -       1       anvil
scache    unix  -       -       -       -       1       scache

127.0.0.1:10025     inet    n   -   y   -   -   smtpd
    -o content_filter=
    -o local_recipient_maps=
    -o relay_recipient_maps=
    -o smtpd_restriction_classes=
    -o smtpd_helo_restrictions=
    -o smtpd_sender_restrictions=
    -o smtpd_recipient_restrictions=permit_mynetworks,reject

    -o mynetworks=127.0.0.0/8
    -o strict_rfc821_envelopes=yes
    -o smtpd_error_sleep_time=0
    -o smtpd_soft_error_limit=1001
    -o smtpd_hard_error_limit=100

smtp-amavis unix -  -   y   -   2   smtp
    -o smtp_data_done_timeout=1200
    -o disable_dns_lookups=yes
#
# ====================================================================
# Interfaces to non-Postfix software. Be sure to examine the manual
# pages of the non-Postfix software to find out what options it wants.
#
# Many of the following services use the Postfix pipe(8) delivery
# agent.  See the pipe(8) man page for information about ${recipient}
# and other message envelope options.
# ====================================================================
#
# maildrop. See the Postfix MAILDROP_README file for details.
# Also specify in main.cf: maildrop_destination_recipient_limit=1
#
maildrop  unix  -       n       n       -       -       pipe
  flags=DRhu user=vmail argv=/usr/bin/maildrop -d ${recipient}
#
# See the Postfix UUCP_README file for configuration details.
#
uucp      unix  -       n       n       -       -       pipe
  flags=Fqhu user=uucp argv=uux -r -n -z -a$sender - $nexthop!rmail ($recipient)
#
# Other external delivery methods.
#
ifmail    unix  -       n       n       -       -       pipe
  flags=F user=ftn argv=/usr/lib/ifmail/ifmail -r $nexthop ($recipient)
bsmtp     unix  -       n       n       -       -       pipe
  flags=Fq. user=bsmtp argv=/usr/lib/bsmtp/bsmtp -t$nexthop -f$sender $recipient
scalemail-backend unix  -   n   n   -   2   pipe
  flags=R user=scalemail argv=/usr/lib/scalemail/bin/scalemail-store ${nexthop} ${user} ${extension}
mailman   unix  -       n       n       -       -       pipe
  flags=FR user=list argv=/usr/lib/mailman/bin/postfix-to-mailman.py
  ${nexthop} ${user}

dovecot   unix  -       n       n       -       -       pipe
  flags=DRhu user=vmail:vmail argv=/usr/lib/dovecot/deliver -f ${sender} -d ${recipient}

mysql/transport_maps.cf

user = user
password = password
hosts = 127.0.0.1

dbname = postfix

query = SELECT target FROM transports WHERE hostname = '%d' AND active = 1

mysql/virtual_alias_domains.cf

user = user
password = password
hosts = 127.0.0.1

dbname = postfix
select_field = domain
table = domains
where_field = domain
additional_conditions = AND active = 1

mysql/virtual_alias_maps.cf

user = user
password = password
hosts = 127.0.0.1

dbname = postfix
select_field = forward
table = aliases
where_field = source
additional_conditions = AND active = 1

mysql/virtual_mailbox_maps.cf

user = user
password = password
hosts = 127.0.0.1

dbname = postfix

query = SELECT mailbox_path FROM users WHERE address = '%s' AND active = 1

Best Answer

Below is a config "stub" for also checking outgoing messages.

In main.cf:

smtpd_sender_restrictions = 
   check_client_access cidr:/etc/postfix/internal_clients_filter

And: /etc/postfix/internal_clients_filter

192.168.0.0/24 FILTER smtp:[127.0.0.1]:12501
10.0.0.0/24 FILTER smtp:[127.0.0.1]:12501

(you could also do this in other ways for logged in users, ip, from etc..)

Use a policybank in Amavisd-new:

$interface_policy{'12501'} = 'INTERNAL'; 
$policy_bank{'INTERNAL'} = {  # mail originating from clients in cidr:/etc/postfix/internal_clients_filter
  bypass_spam_checks_maps   => [0],  # spam-check outgoing mail 
  bypass_banned_checks_maps => [0],  # banned-check outgoing mail 
  bypass_header_checks_maps => [0],  # header-check outgoing mail  
  forward_method => 'smtp:[127.0.0.1]:12502', # relay to Postfix listener on port 12502
};

And the reinject path in postfix:

127.0.0.1:12502 inet    n    -    n    -    -    smtpd
    -o smtpd_recipient_restrictions=permit_mynetworks,reject
    -o smtpd_restriction_classes=
    -o smtpd_delay_reject=no
    -o smtpd_client_restrictions=
    -o smtpd_helo_restrictions=
    -o smtpd_sender_restrictions=
    -o mynetworks=127.0.0.0/8
    -o smtpd_data_restrictions
    -o smtpd_end_of_data_restrictions=
    -o local_header_rewrite_clients=
    -o smtpd_error_sleep_time=0
    -o smtpd_soft_error_limit=1001
    -o smtpd_hard_error_limit=1000
    -o smtpd_client_connection_count_limit=0
    -o smtpd_client_connection_rate_limit=0
    -o smtpd_milters=
    -o local_recipient_maps=
    -o relay_recipient_maps=
    -o receive_override_options=no_header_body_checks,no_unknown_recipient_checks,no_address_mappings