I’ve been setting up three new domains on an Exchange 2003 server for a few days. It really isn’t that difficult, but it’s taken me a bit to get used to working with 2003. It’s a lot different (a lot more integrated) than previously. Of course, 2000 versions may have been as well, but I’ve never – knowingly – worked on an Exchange 2000 system, so that could be part of it. Quite a jump from Exchange 5.5.
Anyway, it’s never been particularly difficult to set up another domain on an Exchange server, and then to assign additional – or even different – domains to different email addresses, and on to users. But I had all that set up and it still wasn’t working. Everything worked well internally, but when I tried to send email to one of these new domains from an external account (not on that server), it returned a dreaded 550: Unable to Relay error. I was stumped.
What got me even more was that I had set up one domain previously and it was working. But I couldn’t find the problem. Everything checked out. Finally I stumbled across this article at Experts Exchange. I’ve never had good luck submitting questions at EE, but I’ve had decent luck finding answers. In this case, I almost gave up on the page before I found the resolution.
It turns out that I hadn’t (yet) set up a recipient policy for the new domains. In that policy, you set up SMTP addresses for the users the policy will affect. On those SMTP address pages, you tell Exchange 2003 that it’s able to accept mail for that domain. So I set up a new policy all quick-like, gave it an address for that domain, and what do you know? It worked. Sweet. Just took me a while to find it.
I’m still not able to get those policies to apply worth a damn, but at least I found one good use – rather, one necessary use – for them.