SpamAssassin

[x] AS_ROOT        Run spamd as root (recommended)
[x] SSL            SSL protocol support
[x] MYSQL          MySQL database support
[x] DKIM           Verify DKIM records (mail/p5-Mail-DKIM)
[x] SPF_QUERY      Verify SPF records (mail/p5-Mail-SPF)
(x) GNUPG2         GnuPG 2 (security/gnupg)

# No required options

Configuration

The SpamAssassin configuration is located in the /usr/local/etc/mail/spamassassin/ directory, the main configuration file is local.cf. In this example we keep the default configuration.

The spamd process is started under the spamd user identity and as it is to set up a server type usage, only the global configuration will be considered (ie: no user configuration).

spamd_enable="YES"
spamd_flags="-x -u spamd --socketpath=/var/run/spamd.sock"

Usage

The spamc command will allow to ask the SpamAssassin daemon to decide on the status of the message. Below, messages weighting more than 100K or taking more than 10s to analyze will be considered as valid. This command is of course rarely invoked manually as it is integrated into the mail server operation.

spamc -t 10Maximum processing time -s 102400Maximum message size for analysis -U /var/run/spamd.sock < message

Rules can be updated (and should) using:

sa-update
sa-compile

Integration

Postfix

It is possible to apply SpamAssassin using either a content filter or milter (mail filter)

Content filter

The master.cf defines how the client program connects to the service and what daemon is invoked when a service is requested. The original configuration is modified to allow e-mails analysis by SpamAssassin

• The content_filter=spamassassin filter is applied to smtp:

  smtp      inet  n       -       n       -       -       smtpd
    -o content_filter=spamassassin
  

• An entry is added for spamassassin:

  spamassassin unix -     n       n       -       -       pipe
  user=nobody argv=/usr/local/bin/spamc -t 10Maximum processing time -s 102400Maximum message size for analysis
    -U /var/run/spamd.sock
    -e /usr/local/sbin/sendmail -oi -f ${sender} ${recipient}
  

Milter

Milter socket is added to the postfix configuration (if multiple sockets are to be used, they are coma-separated):

# Milter
smtpd_milters           = unix:/var/run/spamass-milter.sockCommunication socket  # From smtpd daemon
non_smtpd_milters       = unix:/var/run/spamass-milter.sockCommunication socket  # From submission

The spamass-milter daemon must be enabled at startup, it will allow communication between the postfix milter and SpamAssassin, in the example below processing will be limited to 10s and to message size below 10Mo:

# SpamAssassin milter interface
# Limiting processing to 10s and to message below 10Mb
spamass_milter_enable="YES"
spamass_milter_localflags="-- -t 10Maximum processing time -s 102400Maximum message size for analysis -U /var/run/spamd.sock"
spamass_milter_socket_group="mail"
spamass_milter_socket_mode="660"