Undeliverable Mail to specific domains

[Jenny Crooks]

Using Outlook (98 and 2000) I cannnot send to various
domains. I used to be able to (using the same ISP and
the same domains) but it has stopped working. I get the
following error message:-
"The following mail could not be delivered.
Reason: Unable to deliver message to (e-mail address removed) (and
other receipients in the same domain). Please check if
address is correct."
Any ideas?

 

[Lanwench [MVP - Exchange]]

Check with your ISP - if you aren't hosting your own SMTP server on site,
it's either a problem on their end or on the recipient's.Outlook is just an
e-mail client; once the mail is sent from Outlook to your SMTP server,
Outlook is out of the loop.

 

[Jeff Stephenson [MSFT]]

You might try turning on authentication to your outgoing server (use the
"Outgoing Server" tab for the account).