I usually don’t write about geeky problems. However I just lost the entire morning troubleshooting a weird situation with Microsoft Exchange 2003 and I’d like to understand it. If I asked you to read this, read on…
The problem was that Exchange’s POP3 connector was saying it had retrieved a user’s email and delivered it into their mailbox. However when we looked in the mailbox, the email wasn’t there. Nor was it in any of the “undeliverable” queues. Nor were there any error messages. I think I’ve solved it — or at least figured out a workaround — but I’d like to understand Exchange’s behaviour here. So here goes…
This is a relatively-new server running Microsoft Small Business Server 2003, fully patched, with (of course) Exchange 2003. It does not accept email directly via SMTP, except on the local LAN; all email from external addresses is brought in using the POP3 Connector from mailboxes in a shared hosting account on a Linux server which is under my control.
The primary email domain is
maindomain.com.au. Each user has a base email address of the form
email@example.com, and some users have
firstname.lastname@example.org added and marke as their primary address. Some users also have addresses in other domains, such as
email@example.com, which I’d added using the “Manage Users” tool in SBS’s GUI.
All this was working OK, and still is.
However on the weekend I added another additional domain, let’s call it
problematic.com.au, and two more users. For these users, I wanted
firstname.lastname@example.org to be their primary address in Outlook, so I added the SMTP addresses to their account in the usual way, set them as primary addresses, and then added the relevant POP3 Connectors. POP3 connector downloads the email OK, and the logs would show that it was successfully delivered into the mailbox
email@example.com. However it wasn’t. Email to
firstname.lastname@example.org failed silently in the same way.
Here’s the weirdness…
If I set the user’s primary email address to
email@example.com, then both
firstname.lastname@example.org start working. Change it back and they fail again.
Also, the second user, “Sue Smith”, was
email@example.com and the primary address and
firstname.lastname@example.org as the add-on. Both failed. If I flip them so
email@example.com is the primary email, then
firstname.lastname@example.org starts working but
email@example.com still fails.
This is presumably because the underlying Windows login is
ssmith and not
sue. But why should this matter if the email address is listed in the user’s account as an SMTP address?
It looks like email is only accepted if the primary email address is within the server’s primary domain, but not if an address in another domain is set as the primary — even though both addresses are attached to the user. And, as it happens, even when
problematic.com.au is added to the server’s default recipient policy.
Am I understanding this correctly?
And, the final scary question… Since there’s nothing in the delivery or undeliverable queues, has the inbound email which didn’t arrive been lost forever?