This KB article is thanks to the university of Illinois at Chicago and can be found here http://accc.uic.edu/answer/how-manually-update-your-copy-global-address-list-gal-outlook

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When changes occur within the main (Global Address Book) on the Exchange server; computers running Outlook 2007 and 2010 may not automatically receive the updates. When this happens you may be missing new entries, see non-existent entries, or notice incorrect entries. Updating your address book synchronizes the cached Address Book with the Global address book, and may fix instances of mail that is bounced back to the sender.

Note: In order for some GAL entries to show up properly you may need to turn off Cached Exchange Mode. Please visit the document on How to turn on or off Cached Exchange Mode  Outlook 2010.

Outlook 2010

1. Click the File Tab, Click on Account Settings, and then click Download Address Book. (screengrab attached)
   
   
2. In the Offline Address Book dialog box, make sure that the Download changes since last Send/Receive check box is checked then click OK. (screengrab attached)
   
   
3. Your Outlook Global Address Book is now up-to-date.

Outlook 2013

Note: Please make sure cached mode is turned on.

1. Select the Send/Receive tab on the Ribbon.
2. Click Send/Receive Groups and then click Download Address Book.
3. Click OK.

Outlook 2011 (Mac)

Outlook 2011 for Mac does not use Exchange Cached mode and directly connects to the Global Address Book. In this case your global address book will update each time Send/Receive is pressed.

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"How to Manually Update Your Copy of the Global Address List (GAL) in Outlook." Academic Computing and Communications Center. University of Illinois at Chicago, 12 Sept. 2013. Web. 23 Sept. 2014.