If you are writing to someone who has a doctorate or medical degree, use the abbreviated form: "Dr." However, for other titles, such as professor, judge, rabbi, etc., write out the full title and capitalize it. For example, your salutation in a letter to a judge would be, "Dear Judge Barnard." Or, if your correspondence was with a rabbi, you might write, "Dear Rabbi Williams."
Parts of a Business Letter. Business Letter is a letter which is used by organizations to communicate in a professional way with customers, other companies, clients, shareholders, investors, etc. Business letter uses formal language and a specific format.