SMTP-time bayes filtering

Russell,

• Requiring people to register sucks.
• So does folding your feed

... but I ranted on those two before already on this blog, so won't repeat that. What I wanted to say:

Of course it's possible to do bayesian filtering at SMTP time. If you use the exiscan features of Exim 4 (available in the mainline since exim 4.50, or as a separate patch before that), you can run external programs (virusscanners and/or SpamAssassin's spamd) on the mail data. Read section 40, "Content scanning at ACL time", of the exim4 info file for the documentation.