My husband received his interview request via e-mail and a phone call as well to make sure he got the e-mail. This was on November 14th and his interview was on November 26th. I was not required to be there, but I couldn't stand the thought of not being there so I flew down for it- I also felt it was important to go so they could see us together as a bonafide couple, etc. Right before the interview, the Visa Officer asked to see me briefly but she did not ask me any questions at all- just looked at me while I stood there awkwardly and then she said I could go back out to the waiting area. Anyways hopefully your spouse won't have to go through the nervewracking interview process, but that was my experience with it.