The highly effective Spamcop, Spamhaus, Protected Sky and NIXSpam anti-spam blacklists are preinstalled on all servers.
In addition a number of content based spam filters are available for activation for each mailbox. All detected spam is moved into a separate IMAP folder called "Spam".

The Default Spam Filter, a general filter to block common spam messages, is pre-activated for all accounts. If no spam filtering is desiered this filter can be deactivated with the Spam Filter control panel.

The Spam Filter control panel also has options to activate additional filters:
Mail Syntax Check - A syntax check of the mail header and body.
Executable Attachments - A filter to block executable attachments, including many viruses and computer worms.
Zip Attachments - A filter to block zip attachments. Zip files may contain viruses and computer worms.



In addition there are filters for specific character sets:
East Asian Mails - A filter to block mails using East Asian character sets.
Cyrillic Mails - A filter to block mails using Cyrillic character sets.
Arabic Mails - A filter to block mails using Arabic character sets.



If mail is incorrectly identified as spam, you can configure the spam filter system to allow future messages from the sender to bypass spam filtering (Approved Senders).



The additional Spamcop, Spamhaus, Protected Skyand and NIXSpam anti-spam blacklists can be configured with the Settings -> Mailserver Settings control panel.
The content based filter system is based on procmail. Global settings can be located in the /etc/procmailrc file. More information is available in the procmail man pages.