We recently decommissioned our aging Exchange 2007 Server and switched to using Office 365 for Email.
One quirk of the new system was that some users were having difficulty accessing their Out Of Office (Automatic Reply) Settings when using Outlook 2010 or 2013.
|Your automatic reply settings cannot be displayed because the server is currently unavailable. Try again later.|
There seemed to be no real pattern to this, and many suggestions were offered, non of which worked for us.
The simple solution I eventually stumbled upon was to ensure that “Exchange Web Services” was enabled for each Mailbox within Office 365: Active Users => UserName => Mail Settings => Email Apps
I have no idea why this is required, but it would appear that MAPI doesn’t support the full functionality of Exchange when using Outlook.