Qexplore

Qexplore enables a Qmail server to analyze emails.
Its main features are:
- it can reject viruses using Clam Antivirus (http://www.clamav.net);
- it can check for spam using SpamAssassin (http://spamassassin.apache.org);
- it can block emails with particular attachment extensions during the SMTP communication using Reformime (http://www.courier-mta.org/reformime.html);
- it can "rate-limit" messages that an email address can send in a defined amount of time using an embedded db through SQLite (http://www.sqlite.org).
Unlike other scanners for Qmail, such as Simscan or Qmail-Scanner which are inline scanners, Qexplore is an offline scanner that first write an email to a queue resident on disk, closing the qmail-smtpd communication.
It than (offline) analyzes this email to check for virus and/or spam. This design solves the problem of highly traffic smtp servers in wich a lot of concurrent SMTP connections can deny access of incoming/outgoing emails because the system is busy.