<div>
<div class="content wysiwyg-content">
I have an Exchange 2010 server. &nbsp;Clients are a mix of Outlook 2007 and Outlook 2013. &nbsp;Server has been in place for a few years now. &nbsp;When the server was installed, I created individual Address Lists based on locales. &nbsp;Up until several weeks ago, the default Address Book has been the GAL. &nbsp;Now, the default Address Book for some users has changed from the GAL to one of my created Address Lists. &nbsp;I can manually change it back per user by going into the Outlook Address Book settings. &nbsp;<br />
<br />
What would have caused this to happen and how can I change the default back for all users without going to each workstation one by one?
</div>
</div>


I have an Exchange 2010 server.  Clients are a mix of Outlook 2007 and Outlook 2013.  Server has been in place for a few years now.  When the server was installed, I created individual Address Lists based on locales.  Up until several weeks ago, the default Address Book has been the GAL.  Now, the default Address Book for some users has changed from the GAL to one of my created Address Lists.  I can manually change it back per user by going into the Outlook Address Book settings.  

What would have caused this to happen and how can I change the default back for all users without going to each workstation one by one?

Default Address Book is changing from GAL to an Address List

Exchange is the server side of a collaborative application product that is part of the Microsoft Server infrastructure. Exchange's major features include email, calendaring, contacts and tasks, support for mobile and web-based access to information, and support for data storage.

Exchange

Microsoft Outlook is a personal information manager from Microsoft, available as a part of the Microsoft Office suite. Although often used mainly as an email application, it also includes a calendar, task manager, contact manager, note-taker, journal, and web browser.