> I have Exchange 2000 server. There have been some returned undeliverable > emails sent back to me when I send emails to certain email address. The > error reads: "550 5.7.1 Unable to relay for user@xxxxxxxxxxx" Anyone know > how to fix this? Is it as simple as adding that particular domain to the > allowed "Relay restriction" list? Please, do not even think about adding a domain to that list. Just by you mentioning that means you do not understand what relaying is. I do not know if was you or someone else asked the same exact question not too long ago. I responded you first have to determine where that notice came from. What is the entire message, including headers, that you received with that error notice? John Tolmachoff Engineer/Consultant/Owner eServices For You