Here are three addresses where you can write to Michael.
I recommend you try the first one. Enclose an International Reply Coupon if you´d like him to send you an autographed picture. The response may take a few months- mine arrived after nine- but you´ll surely get one.
Michael Rosenbaum
C/O Tollins/Robbins Productions
Building 160,
Michael Rosenbaum
C/O The Collective
Michael Rosenbaum
C/O Grant & Tani