In a cover letter, keep your remarks brief. Your opening should explain what you are sending and why. In an optional second paragraph, you might include a summary of the information you are sending. A letter accompanying a proposal, for example, might point out sections in the proposal that might be of particular interest to the reader. The letter could then go on to present a key point or two explaining why the writer’s firm is the best one for the job. The closing paragraph should contain acknowledgements, offer additional assistance, or express the hope that the material will fulfill its purpose
When your letter is to more than one person, write out all of their names separately, separating them with commas. For example, "Dear Mr. Hobbes, Ms. Luxe, and Mr. Hopman." For married couples, if one person in the couple has changed his or her name, you only need to use the last name once. For instance, "Dear Mr. and Mrs. Smith."