Outlook clients not updating oab
In order for some GAL entries to show up properly you may need to turn off Cached Exchange Mode.
Please visit the document on How to turn on or off Cached Exchange Mode for (Outlook 2010, and Outlook 20).
A status window will open to indicate that the download is in progress and will close automatically when the download is complete.
(This could take several minutes) Step 2: Uncheck the box next to Download changes since last Send/Receive.