If you are getting corrupt messages with spamass-milter 0.3.0 and [SpamAssassin] 3.1.1, where parts of the message header are showing up in the message body, as \[http://www.nabble.com/Re%3A-Headers-changed-in-3.1.1--p3504730.html described in this message\], then you're running into \[http://savannah.nongnu.org/bugs/?func=detailitem&item_id=16164 this bug in spamass-milter\].  There does not appear to be a fix, yet...