Excessive time doing Send/Receive for messages

[ghostrider]

Version: 2008
Operating System: Mac OS X 10.4 (Tiger)
Processor: Intel
Email Client: imap

From Entourage Mail, when I select Send/Receive the "Messages remaining to be sent" message fairly quickly displays "1" and the blue status bar creeps along, taking 5-10 minutes to complete. I'm on a broadband network connection. This regularly happens. Eventually a 5.1.1 error (unknown or illegal alias) results. I've also received a popup for error 5.3.4 (a message size of x kilobytes exceeds the size limit of y kilobytes computed for this transaction). From another account on the same iMac there is no problem in selecting Send/Receive from Entourage Mail. I am running Entourage ver 12.1.7. Anyone know what may be causing this and what a solution for the problem could be? Thanks in advance!

 

[ghostrider]

I did a search on the "unknown or illegal" alias and found 2 in the outbox. After deleting them, things seem back to normal -- Send/Receive processes for new messages quickly and then ends. So consider this case closed.