SpamAssassin is a mail filter which attempts to identify spam using a variety of mechanisms including text analysis, Bayesian filtering, DNS blocklists, and collaborative filtering databases.
Using its rule base, it uses a wide range of heuristic tests on mail headers and body text to identify "spam", also known as unsolicited commercial email. Once identified, the mail can then be optionally tagged as spam for later filtering using the user's own mail user-agent application.
SpamAssassin typically differentiates successfully between spam and non-spam in between 95% and 100% of cases, depending on what
- Improved automation to help combat spammers that are abusing new top level domains
- Tweaks to the SPF support to block more spoofed emails
- Increased character set normalization to make rules easier to develop and stop spammers from using alternate character sets to bypass tests
- Continued refinement to the native IPv6 support
- Improved Bayesian
- OS X 10.2 or later