base64 transfer encoding defeats rules

[Steven Kiehl]

I just received an email the other day that had mime headers including:

content-type: text/plain
content-transfer-encoding: base64

and the message was encoded in base64, but to the client, it looks like regular text including a geocities spam message.  It was only picked up by the MIME_BASE64_TEXT rule and I have a rule that blocks geocities spam which failed to pick up because the text was all in base64.

Is there a way to get rules to pass for both plain and base64 encoded messages?

My current rule that failed is like this:

body IPBL_6        /geocities\.com\//i
describe IPBL_6    IPBL: Geocities is spam ...
score IPBL_6       5.5