Scr. Romae m. Quint. a 689 (65).

CICERO ATTICO SAL.

‘Letters were usually headed with the name of the writer in the nominative and that of the recipient in the dative governed by the greeting, ‘S.D’ or ‘SAL.’ = salutem dat. The fullness of the names and the greeting was in inverse proportion to the intimacy of the correspondents. In familiar letters only the cognomen was used (Cicero, Attico, &c.), but such apruptness in a formal letter was boorish’.

Correct: Tim to Ed
Correct: Timothy Charles Comeau to Whom it May Concern

Official or other formal communications should give the full style and titles of both the writer and the recipient, and add other greeting, ‘S.V.B.E.E.Q.V’ or the like.

Correct: Timothy Charles Comeau to The Right Honourable Prime Minster Stephen Joseph Harper, SVBEEQV
Incorrect (boorish): Tim to Steve (like, yo!)

Scr. Romae m. Quint. a 689 (65).

CICERO ATTICO SAL.

Petitionis nostrae …

To Atticus
Rome, early July 689 AUC, 65 BC

As to my canvas for the consulship …

(source of Cicero image)