This is my issue:

We are using Exchange 2010 and Outlook 2007. Last week we added a new conference room in Exchange. When I look up the conference room in the Global Address List, it doesn't show up. However, if I delete my .oab files (Offline Address Book) then I can see the new conference room in the Global Address List. When I download the Offline Address Book again, the problem returns. To make this more confusing, some users are able to see the conference room in the Global Address List without removing their offline address book. Is Outlook ignoring their OAB and getting a live copy of the GAL? All users are in cached mode. I am definitely no Outlook/Exchange expert. Am I missing something obvious here? Your help is greatly appreciated.


We figured it out! So as I understood from our Sys Admin, the oab files are generated on one server, and rely on the file replication service on the global catalog servers (we have 2 of them) to copy the oab files to each of the servers. The service was not started on one of the servers and therefore some users were getting old oab's while other users were getting fresh copies. Moral of the story... if you're having this issue, make sure the file replication service is started. Or restart it...


Chances are good that OAB generation is failing for some reason. This does show up in the event-logs of the Mailbox server that does OAB generation, but the logging generally isn't turned on high enough to tell you why OAB generation is failing. For that you need to turn on debug logging for that server.

Set-eventloglelvel -Identity "MSExchangeSA/OAB Generator" -Level High

That will cause Exchange to start detail logging why the OAB isn't generating. You can also trigger OAB generation from PowerShell.

update-offlineaddressbook -Identity "Default Offline Address List"

Which should dump interesting messages into that mailbox server's Application event lot. The exact problem can be any number of things.

  • Done. Unfortunately, or fortunately, it did not produce any errors. The odd thing is that we have some users that can see it and some that can't, it seems to be about 50/50 right now. – Alex Zapata Sep 27 '10 at 20:24
  • On Exchange 2010 the command appears to be: > set-eventloglevel -identity "MSExchangeSA\OAL Generator" -level High – ChrisNZ Nov 29 '11 at 1:01

I've had this problem before - not for Exchange 2010 I will admit (it was Exchange 2003) but the symptoms were exactly the same, so with a bit of luck so is the solution.

Unfortunately I never got to the bottom of why it wasn't working, but I rebooted all of my Global Catalog servers and it magically started working again. If you have more than 1 Active Directory site, just the site you're experiencing issues in should do it.

  • rebooted the Global Catalog servers.... still seeing the same problem. I suspect that this has something to do with the client-side settings. I still haven't figured it out – Alex Zapata Sep 28 '10 at 14:27

Check that Cached Exchange Mode isn't being used in Outlook. If it is (Forgive my O2k3 nomenclature), Tools --> Send/Receive --> Download Address Book. If you don't do this, it can take a substantial amount of time for the clients to update the OAB.

If that's not it, check that LDAP Replication is fine. (You can gather the user's %logonserver% to make sure that the people having the problem aren't isolated to the same DC.)

  • All users are in cached mode. After downloading the address book, still not seeing the new room. I have user's with and without the problem on the same DC. – Alex Zapata Sep 28 '10 at 16:25

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