I recently got through recovering an SBS 2011 server after Active Directory face-planted in the middle of a workday. When I say recover, I mean I repeated the entire migration, using a cleaned up secondary DC - it was a fun weekend (expect another post about that experience). Although I thought we were in the clear, I got a call from the client about 24 hours after we had verified everything was working. He indicated that his iPhone had suddenly stopped receiving mail in the inbox (calendar, contacts, sent items were still fine) and throws up an error after spinning in circles for a few minutes that it "cannot connect to mail server".