You can create filters for the mail, but only on To, From, Subject, CC, Date, Size. If they could filter on other header fields, I could use SpamAssasin on the server to score it, then filter based upon score.

Is there an option to have SpamAssasin change the subject to start with "Spam:" or something you can sort on? I of use popfile with eudora, so I just use a X-Spam header line any sane person would...

Matthew