Exchange bouncing email sent by Outlook

Question

We are trying to move users off Exchange 2007. Following various guides online, we've changed our Accepted Domain to be "internal relay" and created a "Send connector" to relay unhandled email for our domain to an external smart-host.

We then disabled the Mailbox for one Exchange user. The AD user is kept, just the Mailbox disabled (which says it removes mail-user attributes from the AD user).

Several people in the office are using OS X Mail (Snow Leopard with Exchange integration). When sending new email from that client, all works as expected. The email is forwarded to the external smart-host and lands in my Inbox outside exchange.

But for people who are using Outlook clients, sending new email to my account results in a "Delivery has failed to these recipients or distribution lists" message. The error is:

IMCEAEX-_O=FIRST+20ORGANIZATION_OU=EXCHANGE+20ADMINISTRATIVE+20GROUP+20+
[email protected]
#550 5.1.1 RESOLVER.ADR.ExRecipNotFound; not found ##

My guess is that Outlook is caching a direct reference to the deleted user in the address book or elsewhere, causing routing to be ignored. Does that sound right? If so, is there a way to force Outlook to update itself? If not, any other ideas?

Or maybe the issue is that Outlook references the remaining AD user account even though there is no more mailbox?

Edit: A bit more information. When I look in the Message Tracker I see that:

Email sent from Outlook clients to the disabled Exchange mailbox have a recipient of: IMCEAEX-_O=FIRST+20ORGANIZATION_OU=EXCHANGE+20ADMINISTRATIVE+20GROUP+20+ [email protected]

Email sent from Outlook clients to normal Exchange mailboxes are just '[email protected]'

Email sent from OS X Mail clients to either enabled or disabled mailboxes have normal recipients like '[email protected]'.

Solution

I had a similar problem once when a user had been moved to a different Exchange cluster, but Outlook had cached the previous reference and kept trying to send to the previous cluster, even when I specifically selected the user from the Global Address list.

The way I fixed it was in Outlook, start typing the user's name until it auto-suggests the username, use the arrow key to select the name in the auto-suggest list and hit Delete. Try typing the name again and it shouldn't auto-detect it, so you can then select the user from the GAL.

Comments

[learnningprogramming]

If you'd prefer to delete all of these autofill addresses in one action, you can delete the n2k file that stores them (the nickname file). On an XP machine, you'll find that file in C:\Documents and Settings\<username>\Local Settings\Application Data\Microsoft\Outlook. On a Vista or Windows 7 machine, it is in C:\Users\<username>\AppData\Local\Microsoft\Outlook. Just close Outlook, delete the n2k file(s), and restart Outlook and they will all be gone.

[schickb]

A bit scary because then I can't get the account back if things are working (as in my first attempt). I wonder if it could be renamed, or at least the email addr changed when disabled?

[schickb]

Worth trying. Thanks for the addition icky. Although I realized that the Outlook caching theory doesn't explain why server based mailing lists didn't work either.

[Shanmugalakshmi]

I haven't worked with Exchange 2007, but if it's like 2010 in terms of backup/recovery you should be able to just store a backup to recover the mailbox if something goes wrong and you need to bring it back.

[Oskar Duveborn]

Yes usually the NK2 (or in Outlook 2010 the autocomplete stream which follows the user around even in newly created profiles) is the issue here. One can write a powershell script that walks through these files and removes any troublesome X400 entries after a move. Server-based mailing lists has the same issue, if they've been auto-completed once you can still get the issue even if you select it from the GAL manually...

[quadruplebucky]

Yes, Outlook (at least up to 2010) caches any Exchange server address (Distribution Groups too) as X500. This was a pretty big hassle when I moved a client to google apps. NK2Edit is the easiest way to do it in bulk.