The Anti-spam module scans all email for spam using a scoring system of spam indicators as well as using public blacklists. It can be used in a number of configurations:

1. As a transparent gateway that scans email destined for your primary mail server
2. as the MX server that relays to your primary mail server
3. As your primary mail server (which is postfix under the covers).

Blacklist updates are checked for every few hours and automatically installed when new lists are available. The module can be configured to mark mail as spam, block suspected spam, and/or to notify an administrator.