i'm currently running exchange 2010. lately, some emails sent to some of our email boxes are not getting delivered. for example, an outside sender writes an email to user1, user2, user3. user1 and user3 will receive the email but user2 never gets it. there are no failures in message tracking. if that outside sender tries to send an email to JUST user2, message tracking doesn't acknowledge the existence of that email at all. it just doesn't show up. this happens to a few specific email boxes on our server and seems to happen with specific senders too.
how do i start to track down the problem?
Best Answer
If message tracking for user2 nevers shows up with a test email, even from say gmail, then check for undeliverables back to gmail first (or whatever the test sender is).
Try an SMTP test (various online tools or just telnet: http://support.microsoft.com/kb/153119)
Verify that outbound email from user2 works, and check the headers on the remote receiver side to ensure it looks right too (for instance, FROM address is correct)
Finally, if there are layers in the middle, such as an email gateway, SaaS, virus/spam software, etc. you should check those as well.