OUTLOOK2K W/ POP3 DOES NOT SEND MAIL OUT

Outlook 2000 using Internet POP3 was sending mail out but
stopped with the following message:

“Delivery Status Notification(Delay) –

This is an automatically generated Delivery Status
Notification.

THIS IS A WARNING MESSAGE ONLY. YOU DO NOT NEED TO RESEND
YOUR MESSAGE. DELIVERY TO THE FOLLOWING RECIPIENT HAS BEEN
DELAYED. jdoe@yahoo.com

I have McAfee Groupshield installed for MS Exchange
2000.What can I do to resolve this problem as to allow
user to send mail.

Joking