[imp] Unusual outgoing messages

[Stephen A. Cochran Lists]

I was looking around our IMP server for the cause of some runaway  
apache processes, and I found some strange messages in the mail  
queue. We don't allow servers or identities to be set by the user.

H??Received: from 80.89.179.109 ([80.89.179.109]) by  
webmail.dartmouth.edu
         (Horde MIME library) with HTTP; Thu,  5 Oct 2006 15:53:12 -0400

But these messages have a forged from header and are spam. I'm  
wondering how the header might have been forged unless someone is  
posting directly to the compose.php without authenticating first.  
Running Horde 3.1.1 and IMP 4.1.1 (last big security update).

Thanks,
Steve Cochran