Open source and free under the GNU General Public License (GPL).
Quarantines for each mailbox enable users to manage their own spam folders without having to track down an administrator.
Personal Passlists enable users to designate specific email addresses as ""trusted"" without having to bother the IT staff.
Image-based filtering scans images within emails to stop this new pervasive spamming technique.
POP, IMAP & SMTP support.
Reports give a comprehensive view of the spam on your network, including the source of the spam, ham-to-spam ratios, trending and stats per user.