Alpha Man wrote:

Whenever I have a user replying to a message in Outlook, he will
recieve a relay error message. He then has to create a new email and
copy the body over to send it. We are using an exchange 2003 server.
However, he is the only one that pulls from two external POP
accounts. But his default to send is the Exchange server.

Your message did not reach some or all of the intended recipients.

Subject: Test 123 Sent: 03/11/2006 9:09 AM


The following recipient(s) could not be reached:

'Joe User' on 03/11/2006 9:09 AM

554 : Recipient address
rejected: Relay access denied

He's not properly authenticating to the outgoing server of the account that
received the message, since Outlook will reply using the account that
received the original message. See if this helps:
http://support.microsoft.com/kb/290842/en-us
--
Brian Tillman