Recipient address rejected: User unknown in virtual mailbox table (state 13).

Posted on 2012-09-15
Medium Priority
Last Modified: 2012-09-16
Running a SBS 2008 server with Exchange 2007. Email has been working fine up until just the other day. The problem I'm about to describe currently affects only one user. This user was added to AD about 2 weeks ago. Email for this account has been working both internally and externally. All of a sudden, emails from the outside are rejected with "Recipient address rejected: User unknown in virtual mailbox table (state 13).", and only for this user. None of the previously existing accounts experience this issue. To troubleshoot I deleted the account and mailbox and recreated it. No change. I also created a new account/mailbox. This account experiences the exact same problem. Both of these accounts are able to receive email from senders in the domain and neither have any problems sending.

Any help would certianly be appreciated.

Question by:ikellyit
LVL 58

Accepted Solution

tigermatt earned 2000 total points
ID: 38402432
Are you using a Postfix or Exim Linux-based mail gateway in front of your Exchange Server? Perhaps a Linux server or a dedicated appliance / cloud-based service?

The message referring to virtual address tables is not a standard Exchange message, so it suggests that something else is intercepting your mail before it is finally delivered to the Exchange box.

That product/device will need configuring with the email address(es) of the new user(s), since it appears to be storing them for the purposes of rejecting mail addressed to bogus recipients in your domain (to prevent NDR backscatter attacks, for example).


Author Comment

ID: 38403782
You were absolutely correct! We're using a spam service I had forgotten about.

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