In last week (sorry that I post this until now...) I got this autograph from WILLIAM MAPOTHER. I'm very happy because I really like him! I love LOST and I collect autographs from this TV series and he was awesome in this.
In my opinion this autograph is authentic. But all comments about authenticity are still welcome!

Sent : 20 August 2012 (LOR, SAE, 2 photos)
Received : 12 February 2013 (all autographed photos in my SAE)
Used Address :
William Mapother
Abrams Artists Agency L.A.
9200 Sunset Blvd.
11th Floor
Los Angeles, CA 90069
USA
But on envelope he wrote this address, so this should be available now!
William Mapother
Medavoy Management
10203 Santa Monica Blvd
Suite 400
Los Angeles, CA 90067-6439
USA
Photo 1 :

Photo 2 :

Envelope :

Thanks!