Note it can take up to 24 hours for address book changes to propagate automatically.  To speed this up:  

  1. In Outlook 2013/2016 - Click File tab, Click on Account Settings
  2. Then click Download Address Book.  
  3. In the Offline Address Book dialog box, make sure that the Download changes since last Send/Receive check box is checked.

Reference:  https://help.unc.edu/help/365-update-gab/