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OAB Problems?

Often I get asked “My New User XXX is not showing in Outlook GAL”.


First of all, let me clarify some things.

In Exchange (2003 and 2007, and no doubt 2000), you have a Global Address List (GAL) and a Offline Address Book (OAB). The GAL is automatically generated more or less on the fly from AD, and contains all your Exchange-enabled users, groups and fish.

OAB is a copy of this that is available for clients (Outlook 200x) to download.

When you have Outlook 200x in Cached mode, you use OAB

When you have Outlook 200x in “Online” mode, you use GAL

When you access OWA, you use GAL

If you have a Mac and use Entourage, you use a combination of LDAP and GAL 😉

So, if your new user has not shown, the first question is “Are you looking @ the GAL or OAB?”

Most the time customers / end users are looking at the OAB, which means that they are probably just waiting for the horrible lag that MS seem to think is acceptable for OAB to re-generate and become available, which is done every night. Tell them to shush for 24hours and check again.

Occasionally you will find that after 24 hours users still cannot see the new additions. This is slightly more interesting, and now we start the fun.

**Fires up his EXCH2k7 VM to demonstrate**

Ok, so your OAB isn’t updating. First of all, force a manual update


Now, watch your App log, you should see around 3 messages stating that the OABGenerator kicked in, and generated your new OAB.

If, however, you get any “issues” (and it will tell you, but inform you to up the logging to see what was wrong), then you need to change your event log level for OABGenerator in Powershell;



“set-eventloglevel “MSExchangeSA\OAL Generator” -Level Medium”

Then re-rebuild your OAB, and re-look at your App log. You will find all your answers there, and can start your googling!

FYI, most common issue is the SMTP address issue. This is where the SMTP field in AD (Email Address in General tab) doesn’t agree with what the default Reply-To address is set in Exchange. Check the two match, make them if they don’t.

And that, my friends, is OAB debugging in Exchange 2007 =D

Categories: Exchange 2007
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