If two young ladies are to be addressed, the term "Misses" should be used, as:
Havana, Ill., February 20, 189-.
Misses Taylor & Watson, Stenographers,
159 Church Street, Rockford, Ill. Mesdames:
The "Mesdames" may be omitted and the address used alone, but its addition indicates more polish. The translation is "My Ladies." Some substitute for it, simply "Ladies," which is quite proper.
The prefix "Dear" may be omitted wherever desirable, but never write "My dear Miss Halstead," "My dear Madam," or "My dear Sir," unless intimately acquainted.
In writing a social letter the address is omitted or added at close of the letter. A gentleman in private or professional life would be addressed as:
Frederic Guy, Esq. Dear Sir: (or, Sir:)
Or,
Hon. Frederic Guy. Dear Sir: (or, Sir:)
Respectfully yours, John Graceland.