Sometimes the Outlook offline address book (OAB) does not synchronise properly with the Exchange server. To delete the offline file and force Outlook to create a new file, follow the steps below:


  • Rename the folder "Offline Address Book" to any name by adding BAK or OLD at the end.
    C:\Users\%username%\AppData\Local\Microsoft\Outlook
     
  • Start Microsoft Outlook and download an updated version by clicking on "Send-Receive Groups" and "Download Address Book" under the Send/Receive tab.