As per Microsoft: "This typically indicates that the server is configured to route mail back to itself". See MSEX2KDB
for additional information about this event.
As per Microsoft: "This is due to a loop-back situation where the server is configured to loop back on itself and a non-delivery report with a status code of 5.3.5 was generated for recipient". See ME555418
to find out how to solve this problem.
From a newsgroup post: On the SMTP connector, you can have any domain you want, but refrain from having yours or a domain you are authoritative for. The address space denotes SMTP domains that you will like to send mail to. In essence, the SMTP connector in Exchange 2003 is only used outbound, no concept of an inbound SMTP connector really. So having your local domain as an address space is causing you that 5.3.5 loop which means on an attempt to send mail the destination resolved back to the local server. Remove the address space on the connector, and put just a ‘*’ there, so you can "send" to everyone out there on the internet. On inbound, to allow your server to only accept mail for your specific domain name, either on your initial install or manually, you can do this in the recipient policies by having your domain listed there as authoritative or "Exchange is responsible for mail delivery to this organization".