From iRedMail

WARNING: This is NOT finished yet, do NOT apply it on your product server.

Summary

When amavisd detects a spam email, it logs a message to its log file by default. It can also quarantine the email and/or notify an administrator. It can then generate a bounce message to the sender. Finally, it can either accept and deliver the message, or discard the message. Many different configuration variables are involved in these decisions.

Configure Amavisd

Enable a spam quarantine by setting the following variables:

# Set quarantine directory. Default is /var/virusmails.
$QUARANTINEDIR = '/var/virusmails';

# Add level of subdirs to disperse quarantine. Default is 1.
$quarantine_subdir_levels = 1;

# What to do with amavisd-release.
$release_format = 'resend';     # 'attach', 'plain', 'resend'

# Set default action when found SPAM.
$final_spam_destiny = D_DISCARD;

# Filename of SPAM email in $QUARANTINEDIR.
# Below is a complete list of place-holders currently recognized in filename templates:
#   %P  =>  $msginfo->partition_tag
#   %b  =>  $msginfo->body_digest
#   %m  =>  $msginfo->mail_id
#   %n  =>  $msginfo->log_id
#   %i  =>  iso8601 timestamp of a message reception time by amavisd
#   %%  =>  %
$spam_quarantine_method = 'local:spam-%i-%m';

# What to do with SPAM emails.
# - spam-quaranteine: Put SPAM in quarantine directory.
# - postmaster@domain.ltd: Send SPAM to "postmaster@domain.ltd".
# - undef: Do nothing with SPAM.
$spam_quarantine_to = 'spam-quarantine';

# Send notification to admin.
#$spam_admin = "martin.zahn\@$mydomain";

The following symbolic constants can be used in $final_spam_destiny:

• D_DISCARD: Mail will not be delivered to its recipients, sender will NOT be notified. Effectively we lose mail (but will be quarantined unless disabled). Losing mail is not decent for a mailer, but might be desired.
• D_BOUNCE: Mail will not be delivered to its recipients, a non-delivery notification (bounce) will be sent to the sender by amavisd-new; Exception: bounce (DSN) will not be sent if a virus name matches $viruses_that_fake_sender_re, or to messages from mailing lists, or for spam level that exceeds the $sa_dsn_cutoff_level.
• D_REJECT: mail will not be delivered to its recipients, sender should preferably get a reject, e.g. SMTP permanent reject response.

Testing

SpamAssassin ships a sample SPAM mail, you can use Outlook/Thunderbird/Mail.app to open it and send it to your local user, it should be blocked. and you will find similar message in log file (/var/log/maillog or /var/log/mail.log):

Aug 25 23:49:07 r6 amavis[3834]: (03834-01) Blocked SPAM, MYNETS LOCAL [192.168.187.1] 
    [192.168.187.1] <www@a.cn> -> <www@a.cn>, quarantine: S/spam-20100825T234859-SX9PrjWLAKOv,
    Message-ID: <4C753B6A.4020304@a.cn>, mail_id: SX9PrjWLAKOv, Hits: 996.105, size: 995, 7922 ms

You can find quarantined emails here: /var/virusmails/S/spam-20100825T234859-SX9PrjWLAKOv.

You can release this mail with command:

# amavisd-release S/spam-20100825T234859-SX9PrjWLAKOv

References

• Fighting Spam/Viruses with Amavisd-New, Maia and Postfix