I've just completed a server migration from SBS2003 to SBS2008. I'm having a problem on the new server where all but one of the migrated users are having their mail get stuck in the "unreachable domain" queue. Exchange reports that "The mailbox recipient does not have a mailbox database" even though they do have a mailbox and it shows up in the Exchange console. Here's an example:

Identity: SBS2008\Unreachable\2387
Subject: Test mail flow
Internet Message ID: 
From Address: Tim@tigranetworks.co.uk
Status: Ready
Size (KB): 32
Message Source Name: SMTP:Windows SBS Internet Receive SBS2008
Source IP:
SCL: 0
Date Received: 15/01/2010 00:35:59
Expiration Time: 17/01/2010 00:35:59
Last Error: The mailbox recipient does not have a mailbox database
Queue ID: SBS2008\Unreachable
Recipients:  admin@[obfuscated]

Any Exchange experts out there have any idea what might cause this paradoxical situation?


I can't say I've see this one before, but this article looks promising:

  • That article was close but not an exact fit. That's the only reason I didn;t designate this as teh accepted answer. – Tim Long Jan 27 '10 at 3:40

Problem solved - with help from Microsoft. Running the Best Practices Analyzer with the 'permission check' option enabled highlighted the problem. Permission inheritance was blocked on the 'My Business' OU.

Unfortunately the old server had already been decommissioned, so it is unknown whether this condition existed on the old server and simply migrated accross, or wether the problem was introduced on the new server.


Problem: You moved your mailboxes and it all seems to be ok, but then you see that messages are not getting through and the Unreachable queue is full of messages. They show "Last Error" The mailbox recipient does not have a mailbox database." Solution : Using AD Users and Computers, move the users to the MyBusiness - Users - SBSusers OU. UIse ADSI Edit to check that all users are inheriting permissions from the parent OU. Then retry the unreachable queue (from Exchange Manager shell run Retry-Queue -Identity "\Unreachable" -Resubmit $True)

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