One Exchange 2010 issue

When end user use the outlook anywhere to connect company exchange 2010 server from outside, it will come out the Synchronization Log:

**15:18:26 Microsoft Exchange offline address book

15:18:26 Not downloading Offline address book files. A server (URL) could not be located.

15:18:26 0X8004010F**

Can help me to resolve this issue. I have tried many methods but can not resolve it!

Thank you very much.

You need to set the OAB virtual directory for external users. You do that by running the following command (with the proper url. Probably your OWA url):

Get-OABVirtualDirectory | Set-OABVirtualDirectory -InternalURL https://exchange.domain.local/OAB -ExternalURL https://mail.domain.com/OAB