In a business letter or any formal letter you will traditionally use the salutation of.
A. Dear Senator Smith,
This is only slightly different from Dear Senator Smith - however the comma is an important element grammatically that should be included in a formal letter.
Unlike a personal or informal letter, which calls for a comma, a colon is used after the salutation when writing a formal business letter. Never use a semi-colon, em dash, or ellipsis.
