In writing to a man in his official capacity, the following form is correct when there is no street number or when the title is short. Notice that Mr. is omitted.
G. N. Fratt, Cashier,
First National Bank,
Racine, Wis.
The following is correct when the title is long:
Mr. John Frederick Pierce,
Ass't. Engineer of Bridges and Buildings,
607 White Building, Seattle, Wash.
Notice that in the last example, the city and the state are put on the same line as the street in order to make the three lines of about the same length. Four lines might have been used.
The Salutation
If you address one man, the salutation is Dear Sir; as,
Mr. John Pierce,
Seattle, Wash.
Dear Sir:
If you address a firm, the salutation is Gentlemen; as,
Messrs. Brownleigh & King,
Portland, Oregon.
Gentlemen: