How can my users feed back mail for the Bayesian learner?

If you want to set up site-wide use of Bayesian classification, you should set up a way for your users to send in misclassified mail to be "learned" from.

A good way is to set up a mailbox where users can send verified spam, or verified non-spam, for the learner to learn from.

One issue here is that you will need all the headers of those messages for the learner to work effectively, including the Received headers. A few mail user agents strip off those headers. For users using Outlook 2000, get them to use

  (double-click to open the mail in its own window)
      -> Actions
      -> Resend This Message

and bounce it to the mailbox address. Then run a cron job intermittently to learn all the mails in that mailbox as spam (or non-spam).

Another option, and one that's easier for most users to use, is to set up two public IMAP folders on your IMAP server, one for MissedSpam, one for NotSpam.

Then ask your users to move messages that SpamAssassin misses into the MissedSpam folder, and move messages that SpamAssassin marked incorrectly as spam into the NotSpam folder.

You can then run sa-learn from a cron job over those folders to update the Bayesian databases.