If you're running something older than Exchange 2007, there's a chance you're using an incompatible Offline Address Book format.It's worth noting that Exchange 2007 had a glitch that caused the Enable Web Based Distribution checkbox to be grayed-out on the Default Offline Address Book Properties sheet.
This glitch prevented Outlook 2013 clients from being able to download the Exchange Offline Address Book.
To fix this problem, open the Exchange Management Shell and enter the following command to enable the checkbox: The problems we've discussed so far only occur in situations when using Outlook 2013 in a legacy Exchange Server environment, but Outlook 2013 can have trouble downloading the Offline Address Book even in an Exchange 2013 environment.
There are several things you should check: About the author: Brien Posey is an eight-time Microsoft MVP for his work with Windows Server, IIS, Exchange Server and file system storage technologies.
Brien has served as CIO for a nationwide chain of hospitals and health care facilities, and was once responsible for IT operations at Fort Knox.
To determine the URLs currently used, open the Exchange Management Shell and enter the following command: with your domain name in the above command.
So what do you do if the correct external URL is listed but external clients are still unable to download the Exchange Offline Address Book?
One of the reasons for this is that Microsoft has introduced multiple versions of the Offline Address Book over the years.
Outlook 2013 only works with version 4 of the Offline Address Book, which was introduced in Outlook 2003 SP2.
This can happen if Client Access Server using the OAB virtual directory is not properly configured.