Addennum to Rogers Spam Hell 
Forgot to mention, I discovered that during the massive email processing I was doing, there were spawned hudreds of sendmail processes. To the point that we ran out of virtual memory. So I guess the SpamAssassin throttling was a good idea after all. It also implies to me that perhaps Fetchmail was waiting for the sendmail it spawned to confirm delivery, and since the sendmails were not exiting properly or in time (ie before Fetchmail was dying) Fetchmail was refraining from issuing the DELE command. So I take back some of what I said about Fetchmail.
All told, though, this spam crap is starting to bug me. A Ultra10/440 is no longer adequate to handle
one person's spam reliably.