What the problem is:
The Global Address List is not automatically updating when by default it is supposed to.
What is causing said problem:
The error causing the Global Address List to not update is a corrupt file within Outlook. This can happen after a long period of use with outlook and happens for no apparent reason.
How to Manually Update the Global Address List:
- Go to Exchange System Manager and
- Navigate to Recipients -> Offline Address Books.
- In the right pane, right-click the default address book and click Rebuild.