An Outlook user had this complaint:
Some of my contacts are in both the GAL and my local Contacts folder. Outlook updated my contacts (in my contacts folder) with information from the Global Address Book. How to disable this function? The GAL contains outdated information.
This is a feature of the Social Connector, with the automatic updates of contacts enabled by default. A change log is added to notes so you know what was changed. Note: the social Connector is deprecated and may be removed from a future version. It is disabled by default in Outlook 2016. If you enable it, only the search features work.
Change the Update Settings
To change the setting in Outlook 2010 and up (if the Social Connector is enabled), go to the View ribbon, People Pane, Account Settings, Settings button and change the update option from Update without prompting to Prompt before update or Never update.
In Outlook 2003 or 2007, the Account Settings dialog is accessed from Tools, Social Networking Account settings.
While it may be tempting to turn off updating, it defeats one purpose of the social connector: to keep your contacts updated. The change log in the notes field displays the changed data, should it try to update the contact with old information.
This setting is stored in the registry. The key is the same for all versions of Outlook that support the Social Connector. If the key or value does not exist, add it.
0 (Never Sync)
1 (Update without Prompt)
2 (Prompt to sync)
Default setting is Update without Prompting.
Disable Contact Updates Video Tutorial
Disable Contact Sync using Group Policy
Administrators can disable Contact & GAL sync using group policy. It's found under Outlook > Outlook Social Connector in the Group Policy editor. Look for Block Global Address List synchronization.
Value: 1 (no sync)
Administrators can disable this feature using a group policy. For more information, see Disable global address list synchronization for Outlook 2010 in TechNet.
Administrators who want to give their users the ability to update the GAL with current information should see the list of utilities located at Active Directory Management Tools - User Updates