This totally stumped me for a while. I had a few random users getting an 0x80200049 error when downloading the offline address book. I went over everything on Exchange (2010) and everything looked fine and dandy. Even tried resetting the Outlook profile, to no avail.
Well, lo and behold; Outlook uses BITS to download the OAB; and if the BITS queue goes full (60 jobs I think), it stops. Intuitive, right. No mention of BITS anywhere, yet that’s the culprit.
Another indicator of this problem is that you’ll see a bunch of GUID-named folders under the users AppData.
So the fix?
Run BITSADMIN.EXE /RESET on the client computer to reset the BITS job queue, and… tada! Magic.
Also, if you have clients that are stuck when downloading the OAB, just no progress and no error, check the ACL on “C:\Program Files\Microsoft\Exchange Server\V14\ExchangeOAB” on your CAS. Chances are they don’t have access.
And also keep in mind that if you get this ACL problem, it’ll return some time. Either it gets reset during a SP- og RU-install, or during some other maintenance. Most likely related to a redirect you’ve probably set up; but I haven’t been able to confirm that yet.