[Mimedefang] SpamAssassin+MIMEDefang HTML messages Scoring

[Stephen Gurnick]

I have a MIMEDefang(2.63)+SpamAssassin(3.1.9) setup that is catching a lot 
of spam, but specific spam messages are slipping through.  It appears to 
be fairly consistent day-to-day.

If the email is a HTML message, spamassassin will hit on the HTML_MESSAGE 
rule and that's it.  These spam emails are obvious as they contain key 
words and phrases they should be hitting on other rules.

I have a feeling MIMEDefang may be inhibiting the process somehow, since 
if I take one of these spam messages that got through to my inbox and run 
it manually through spamassassin using the command: "spamassassin -t < 
spamemail > spamemail.out" it will score it appropriately and mark it as 
spam.

Again, this happens if the spam email is sent as an HTML message.  If the 
spam is sent as plain text, I don't notice any problems with the scoring.

Any help and suggestions for things to look at to shed some light on what 
might be going here would be greatly appreciated.

Thank you very much.