Try to track how these messages end up in the queue. Are they from a local sender, or have spammers found a way to relay through your server? Make sure strict relaying control is switched on, and that there aren't any AUTH passwords that have been compromised.

/Rolf 

getting alot of this messages, seem to be a result of the foward file sending to external email

--Part_Boundary-3B60EAEF
Content-type: Text/plain; charset=US-ASCII
Content-description: Mail delivery failure report
Content-disposition: Inline

With reference to your message with the subject:
   "Delivery failure notification"

The local mail transport system has reported the following problems
it encountered while trying to deliver your message:

-------------------------------------------------------------------
*** xyz@aol.com
550 5.2.0 Exploit-MIME.gen
-------------------------------------------------------------------

Your mail message is being returned to you in the next part of this
message.

Looks a lot like you are sending out delivery failure notifications for spam messages that contain some kind of virus, which causes aol.com to refuse them.

/Rolf 

Thats what I was figuring, how do I foward only the good messages not the spam ones

If the incoming messages contain some virus it should be possible to catch them with ClamWall. I suppose you already have some anti-spam measures in place, but it might be worth considering to add one more (like SpamHalter, PopFileD, DNSBL, GrayWall, etc).

/Rolf 

Do you know that you sent the mail to aol? It could be spammers sending fake bounce messages with virus payload and forging your address as sender. If you turn on session logging in MercuryE you should get a full record of everything you forward (don't leave it on for too long or you'll fill your disk up).

If it turns out you are forwarding mail with a virus in it, you need to scan it before it gets forwarded.

Okay

I think I found the cause

It appears that in the mercury send queue were messages that could not be delivered.  I stopped mercury cleared the queue and then restarted

All is clear for 4 hours then it started again until I cleared the messages out of the queue.

What is permanent cure for this I have max redilveriery attempts set to 4