I saw a post with a similar question, but did not understand the fix, so here goes.
Exchange server using POP3 connector to retrieve all mail from a domain.
Only using SMTP to relay outbound mail.
Whenever someone outside the company sends email, the email is delivered but the sender recieves:
The following recipient(s) could not be reached:
Blow, Joe on 3/29/2006 7:46 AM
A configuration error in the recipient's e-mail system prevented delivery of this message. Two recipients are configured with the same e-mail address. Contact your administrator.
How do I fix this.
This happens for ALL users in the domain.