Default global address list not updating 2016
If you are not seeing correct contact information in the GAL for someone that has a valid email address (i.e.someone who just received a CUMC email account, a new student, someone who recently changed their directory information) please use the steps below to synchronize your computer's locally cached version of the GAL.Although this topic lists all parameters for the cmdlet, you may not have access to some parameters if they're not included in the permissions assigned to you.
It can be accessed when using a CUMC email account with Outlook and Web Outlook.
Then decommissioning the on-prem servers, leaving two relays on prem.
Should I delete both and recreate a new default one?
This article explains how to manually force an update the global address list in Office 365.
Updating the global address list requires having the Address List Management role.
If it is not updating, you might need to update it again.