Environment Exchange 2010 SP2 and latest rollup running on SBS 2011 latest patches. Network is a simple one internal network NAT'd with a firewall that allows SMTP through a proxy. We get about 1-2K messages a day (90% spam) and no other reports of anything similar are happening. The Issue: We have a user "S" that has not been getting mail from one user"U" that is at client "C" for some time. The circumstances have me perplexed. Other users at our firm do get the e-mail when they are on to: or cc: line."S" gets mail from other users at client "C" fine."C" shows no rejection/NDR or any indication of failure.We show the message coming through fine at the firewall, our 3rd party antispam agent, showing the proper user is getting it.However, when the message gets to another agent (Exclaimer Auto Responder,) the user "S" is not listed in the "to" field. This agent is not applying any rules to this message and is just passing it along like most of our inbound mail.I've tried to "find" the message using message tracking but the message only shows in other users' mailboxes.The user "S" has no rules, views, or redirection applied. The message is not in junk mail or accidentally put in another folder or even deleted or hard-deleted. I've tried to rebuild her Outlook cache with a new profile and it doesn't make a difference. She just doesn't get the mail. Company C is claiming no issues on their end, and I wouldn't expect them to. We have had other issues with this company before relating to e-mail, but I don't think they are related. I can list them later if anyone wants. I suspect that the issue is somewhere between our Antispam agent (ORF, which whitelists all e-mail from company C and works fine) and the Exclaimer Auto-Responder (also working fine). How can I find the cause of this? Exchange Message tracking is no help here.no

I would disable any AV, disclaimers, AS on the Exch server and test. Take a pipeline trace Also, disabled agents - Get-TransportAgent to see what's there.Sukh

hi, How about your issue,any update? If Sukh's solution can help you to fix your issue,please remember to mark as answer. thanks, CastinLu TechNet Community Support

Sorry for lack of response. No AV on the server. Not going to disable disclaimers, they are critical for our line of work, and I don't understand why this would only impact a single user. I was able to work around the issue by having the sender use first.last@domain.com instead of first_last@domain.com. All users have at least both of these aliases, and all other users receive mail fine. This isn't worth disabling systems for or using the ominous impacting pipeline trace (which Microsoft plasters warnings all over the howto guide about. I'll give you both helpful, what the heck. no