UPDATE: See the latest DNSBL Safety Report for current recommendations.

SpamTips.org occasionally looks at the results of Spamassassin’s nightly masscheck at RuleQA in order to analyze the performance and safety of add-on DNSBL’s. It is vitally important to know how a DNSBL is performing before deciding if it is a good idea to use it.  Many of the below DNSBL’s were tested because they indicated strong performance in other comparisons. Our analysis demonstrates that raw detection numbers can be misleading, as ham safety ratings and overlaps with other rules must be taken into consideration.

Today’s report examines Hostkarma, SpamEatingMonkey, Tiopan, UCEProtect, Mailspike, and Nix Spam and Lashback UBL.  Recommended scores below are what I personally use in production.

UPDATE: See the latest DNSBL Safety Report for current recommendations.

This blog will occasionally look at the weekly DNSBL masscheck statistics.  Our measures indicate that the performance and safety of the smaller DNSBL’s can vary wildly from month to month.  If you depend on DNSBL’s, you should pay attention to these safety reports in order to protect your users from the likelihood of false positives and losing mail to the spam folder.  This should help you as a SpamAssassin sysadmin to decide which add-on DNSBL’s to use, and what score to assign with the goal of maximizing spam filter safety.

Here is a quick look at the safety and efficacy of a few add-on and existing DNSBL’s for SpamAssassin.  Today’s report looks into Hostkarma, Spam Eating Monkey, Tiopan, MailSpike, NiX Spam and PSBL.