Try contacting Samantha at this address:
Samantha Mathis
You may also want to include a self-addressed stamped envelope (SASE), since stars tend to reply more often with these.
But on June 25, after about 3 months of waiting, a friend of mine recieved a beautiful 8X10 photo, autographed by Samantha. It is not done by an autopen, and it was definitely worth waiting for. She didn't even include a SASE or anything. Now, hopefully I'll get a reply as well! The above address is the one that she used.