10 Using Anubis to Process Incoming Mail

Historically Anubis was designed to process outgoing mail. Support for processing incoming mail was added in version 4.1.

To process incoming mail, Anubis must be started as mail delivery agent from your MTA configuration file. The invocation line must contain ‘--mode=mda’ option, that tells Anubis to act in mail delivery mode. In this mode, Anubis receives the message from standard input, processes it using configuration file sections named incoming-mail-rule (see section incoming-mail-rule) and finally calls local mailer to actually deliver the modified message. The local mailer must be given using ‘--local-mta’ option.

Let’s summarize the special features of mail delivery mode:

1. The mode is enabled by the ‘--mode=mda’ option in the command line or mode mda setting in CONTROL section of the anubis configuration file. It the ‘--mode=mda’ option is used, the mode setting in the configuration file is ignored.
2. Anubis uses local mailer to actually deliver messages. The mailer invocation line can contain meta-variables %sender and %recipient, which will be replaced by the actual sender and recipient email addresses before starting the mailer.
3. A special option ‘--from’ may be used in Anubis command line. This option sets sender email address (see %sender meta variable above). It implies ‘--mode=mda’. If the option is not given, GNU Anubis will deduce sender address from UNIX ‘From ’ header or, if it is not present, from the value of From SMTP header.
4. In MDA mode, Anubis takes recipient email addresses from the command line.
5. Anubis uses a separate rule section for processing incoming mails. The default section name is ‘INCOMING’. It may be overridden in system configuration file using ‘incoming-mail-rule’ (see section incoming-mail-rule).

The following discussion explains how to configure Anubis in MDA mode with different mail transport agents.

• Sendmail

  If you use mc file to generate ‘sendmail.cf’, use LOCAL_MAILER_PATH and LOCAL_MAILER_ARGS as shown in the following example:

  define(`LOCAL_MAILER_PATH', `/usr/local/sbin/anubis')
  define(`LOCAL_MAILER_ARGS',
         `mail --mode=mda -l '/libexec/mail.local -f %sender %recipient')
  

  If you prefer to directly edit ‘sendmail.cf’, use M macro to declare Anubis as a local mailer. For example:

  Mlocal, P=/usr/local/sbin/anubis,
          F=lsDFMAw5:/|@qSPfhn9,
          S=EnvFromL/HdrFromL, R=EnvToL/HdrToL,
          T=DNS/RFC822/X-Unix,
          A=mail --mode=mda -l '/libexec/mail.local -f %sender %recipient' $u
  

• Exim

  With exim, you will need to declare appropriate transport and director in ‘exim.conf’:

  # transport
  mail_local_pipe:
    driver = pipe
    command = /usr/local/sbin/anubis --mode=mda \
               -l '/libexec/mail.local -f %sender %recipient' $local_part
    return_path_add
    delivery_date_add
    envelope_to_add
  
  # director
  mail_local:
    driver = localuser
    transport = mail_local_pipe
  

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