MailChariot's mission is quite simple:
- Take your incoming mail (from /var/spool/mail for example),
- Filter your emails through a spam filter like SpamAssassin,
- Depending on the verdict put your email into ham or spam mailbox,
- If you disagree with spam filter's choice you can move the email into notham
or notspam mailbox and MailChariot will let spam filter know that it was
wrong. Mail that you put into notspam folder will be moved to ham folder
afterwards.

Notice that all of this is mail reader agnostic. Marking messages as spam only
requires moving an email to a mailbox, so it's not important if you use
Thunderbird, Mutt or whatever.

If you are on a shared host without root privileges and your admins do a bad
job of keeping your mailbox spam free, you can use MailChariot to filter the
mail yourself.