In order to reflect any changes or updates made to the Global Address List, you can force Outlook to download a new copy of the GAL.
–For Instructions for Outlook 2007 –For Instructions for Outlook 2011 –For Common errors and troubleshooting Step 2: Uncheck the box next to Download changes since last Send/Receive.
I am not an Exchange administrator by any stretch of the imagination, I support the Outlook application. Whenever this person would address e-mails to certain people they would get that pesky mail tip that would say "This e-mail message cannot be delivered to (recipient name) because the e-mail address is no longer valid".
(This could take several minutes) Step 2: Uncheck the box next to Download changes since last Send/Receive.
When changes occur within the main Global Address Book (GAL) on the Exchange server, computers running Outlook 2007, 2010, and 2013 may not automatically receive the updates.
If this is happening, then you may notice missing, non-existent and/or incorrect entries.
Rather than waiting 24 hours for Outlook to update the Offline Address Book on its own, you can force an update via the Send/Receive menu button.
You can disable the option “Download changes since last Send/Receive” to make sure you get a complete fresh copy of the OAB but this could take longer to download.