456, X Street, Y Avenue,
[Subject: Normally bold, summarizes the intention of the letter] -Optional-
Dear Jack Martinez,
It is with profound thanks that I write in regards to the reference you provided for myself. It was much more than I expected and realize what a benefit I have gained because of it. It is this reference that has allowed me to gain a dream position.
My application alone would not have been sufficient to allow me to gain the position and I know that the reference swung the decision in my favor. You are a very respected member of our community and I know that when you make a recommendation people take note.
The time taken to write the reference, and its glowing nature, means a lot to me. You are a busy man and I know that your thoughtful action has allowed me to gain by it. If there is anything that I could do in the future for you, I would ask that you would let me know.