Train spam filters in spam assassin
Email
http://faisal.com/docs/salearn.html
Training with Maildir format
Maildir format is a bit different -- it stores each message in a seperate file within one of three subdirectories ('cur', 'new', and 'tmp'). Instead of pointing sa-learn at a specific mbox or mbx file, you point sa-learn at the directories and it looks at all the files inside:
sa-learn --no-sync [--spam or --ham] [folder/{cur,new}]
For example:
sa-learn --no-sync --spam ~/Maildir/.INBOX.Spam/{cur,new}
or
sa-learn --no-sync --ham ~/Maildir/.INBOX/{cur,new}
(This ignores the 'tmp' directory, which is used as a working directly and is usually empty. You may also wish to ignore the 'new' directory, which lowers the odds of receiving and scanning wrongly-filed mail during a scan. To do that you would just scan folder/cur.)