Update exchange offline Address book
Some time offline address book doesn’t show recent changes we made to the exchange server. To update exchange offline:
Update-OfflineAddressBook -Identity [-Confirm []] [-DomainController ] [-Force ] [-WhatIf []]
To get all the offline address book -> open exchange powershell :
get-OfflineAddressBook
Choose your OAB (Offline Address Book) and type:
Update-OfflineAddressBook -Identity Your_OAB
https://technet.microsoft.com/en-us/library/aa995979(v=exchg.160).aspx