It is only in cases of extreme formality that the expression "Dear Madam" or "Dear Sir" is used. For ordinary social correspondence, the salutation is either "Dear Mr. (Mrs.) Roberts" or "My dear Mr. (Mrs.) Roberts." The use of "My dear" is considered more formal than merely "Dear," except in England where the first form is considered the more intimate.
The form "Dear Miss" or "Dear Friend" may be used on no condition whatever. It is either "Dear Miss Wimberly" or "Dear Madam." It is considered presumptuous, in good society, for a man to address a lady as "Dear Mrs. Brown" until she has first dropped the formal "my" in her correspondence with him.
The strictly formal method for addressing a letter to a man by a woman who is a total stranger to him, is:
"Mr. John D. Brown,
"Dear Sir."
If he is a distant relative, addressed for the first time, or the friend of a very intimate friend, the salutation may read, "My dear Mr. Brown."
CLOSING THE LETTER
The endings "Very truly yours" or "Yours truly" express a certain formality. Friendly letters are closed with such expressions as, "Yours most sincerely," "Cordially yours," "Very affectionately yours," "Lovingly yours." The latter two expressions are confined largely to intimate friends and relatives, while the others are used when letters are written to new acquaintances or casual friends. The pronoun yours should never be omitted, as it leaves the phrase unfinished and is not complimentary to the person addressed. Thus, closings, such as "Very truly" or "Sincerely" are in bad form.
Always remember in social letter-writing, to make a "graceful exit." An awkward sentence in closing often mars what would otherwise be a perfect letter. Forget certain strained expressions that remain in the mind and demand to be used as closings, merely because they have been used by so many people, over and over again. Make the farewell in your social letters as cordial and graceful as your farewell would be if you were talking to the person, instead of writing. Such kind expressions as "With kindest personal regards" or "Hoping to have the pleasure of seeing you soon" or "With best wishes to your dear mother and sisters" always add a note of warmth and cordiality to the social letter. These should be followed by "I am." It is not considered good form to end a letter,
Hoping to hear from you soon,
Yours sincerely,
but it should be