If you have any scripts, like those used during the failover process, that use this cmdlet for Exchange 2010 you need to update them to set this value each time.

Just add “–AllowCrossSiteRPCClientAccess $True” to the cmdlet line when calling Set-DatabaseAvailabilityGroup, this assumes  you want to allow cross site RPC access without requiring your users to restart Outlook when their active database is moved to another AD Site.

Set-DatabaseAvailabilityGroup –AllowCrossSiteRPCClientAccess $True.

I’m pretty sure  I’ve seen this value reset back to $False with SP2 (RU unknown) also, so this “bug” might have existed before SP3. This switch was added, or really it started working, in SP2 RU3.

See this blog post for more details:
http://blogs.technet.com/b/rmilne/archive/2013/05/08/exchange-2010-dag-allowcrosssiterpcclientaccess-reverts-to-false.aspx

For general Exchange 2013 questions or to discuss non-support topics join the “Microsoft Exchange 2013” Facebook group I admin: https://www.facebook.com/groups/MSEX2013

For community based support goto TechNet forums: http://social.technet.microsoft.com/Forums/exchange/