Outlook NDR for internal mail

[Guest]

We are running Exchange 2003 on SBS R2 and Outlook 2003. Periodically we get
NDR's on internal messages that say :

"The message could not be delivered because the recipient's destination
email system is unknown or invalid. Please check the address and try again,
or contact your system administrator to verify connectivity to the email
system of the recipient.
<ourdomain.com #5.1.2>"

This seems to be very intermitent and, of course, usually happens to our CEO
who finds it to be a big deal.

In the past I have manually run the Recipient Update Service which seemed to
correct the issue for a while. The only changes to the server was a restart
a couple days ago. I have also searched for the 5.1.2 error but did not find
anything that seems applicable.

Any help from the pros would be greatly appreciated! Thanks in advance.

 

[Guest]

I have the same issue and would like to find a solution. When I get an NDR I
try to resend the same message and if I check the recipient's name its tab
for email address is empty.#
Regards

 

[Guest]

Update:

We have isolated and reproduced the issue. It appears that when you click
on To: and select the recipient from our shared Contacts list that is set up
as a Public Folder, you will get the NDR. If you type the name in the To:
field it works as intended and the mail goes through.

Still searching with this new information.