Dear Mr. Clint
I am sure that this letter will find you busy sorting out applicants to your company. As you are one of the best organizations around, I am sure that the line of applicants to your firm is long.
I know of someone who has made an application to your good office sometime ago. I have had the opportunity to work with him before and I can vouch for his character. He has shown so much diligence in his work and has been one of the top employees of his former department. His resume will have all the details for you.
I have made this reference for his character with no hesitation at all. But should you find that my assessment of him was wrong, please disregard this letter and take no offense. My only intention was to help you.
Thank you very much.