Office 365, Email, Exchange, Offline Global Address List needs to be synchronized
You can manually force Outlook 2016/365 to update the GAL by using the following steps:
Offline Global Address List needs to be synchronized. The GAL is not resolving contacts.
- Click on File
- Click on Account Settings
- Select Download Address Book
- In the dialog box, check Download changes since last Send/Receive, and Choose the \Offline Global Address List.
- Click OK.