ISPs of all sizes run Apache SpamAssassin to provide email services. While free and effective, it is a resource intensive and high maintenance anti-spam solution.
Maintaining performance
Maintaining an acceptable level of spam filtering performance requires constant updating of Apache SpamAssassin. And without the resources of a commercial solution, it can be difficult for Apache SpamAssassin to keep up with the latest spam strategies and many users have reported a marked reduction in the effectiveness of open source blocking techniques such as grey-listing and RBLs.
Maintaining effectiveness
Those experiencing multilingual spam problems using content filtering become increasingly difficult and prone to false positives. And without effective connection management to eliminate unwanted connections and optimiz bandwidth, Apache SpamAssassin's procesessor intensive content filtering can be quickly overloaded by high spam traffic.
All Apache SpamAssassin and open-source MTA users would benefit from adding traffic shaping to their systems to improve spam protection and reduce load on the Apache SpamAssassin servers.
