Identify Your Reader
A response letter should be addressed to a person from whom a request or inquiry has been received. That person's name will be found in the complimentary close of a previous inquiry letter and should be placed in the inside heading and the salutation of your response. It should also be included on the top line of your envelope.
Remember that people do business with people first, businesses second. When you address your reader by name, you recognize their importance and value as an individual human being. In the inside heading of the sample response letter the reader is identified by both his name and the title he holds.