2365 S Mayfield Ave
Chicago, IL 60652
[Subject: Normally bold, summarizes the intention of the letter] -Optional-
Dear HENNERY SMITH,
I much appreciated the help you gave me when covering my work during my recent absence from the office. I was worried that many of our clients would suffer because of a lack of attention to their needs, but you handled even the most difficult of accounts with true professionalism. Please let me know if there is anyway that I can return the favor.