A true gentleman.
Well, the next time you are talking about them behind their back you could always just say something nice. :)
Always say thank you and mean it. And a nice compliment would be nice as well.
Say "Thank You"
I still like to send a good old fashioned thank-you note.
That is always special when someone takes the time to personally write something to you. :)
Say something along the lines of ''I appreciate the fuck out of you, keep doing what you're doing''