Dear Mrs. (Name),
It is only yesterday that I received a letter from Munish, through which I came to know that you have appointed him Office Assistant in your firm. I am indeed very much thankful to you for this gesture of help to my friend’s son, Munish. He is a man of the confidence and trust, I am hopeful he will be successful in his job and will really come upto your expectations.
Thanking you one again for the kind favour.