Opening salutations for a letter include: "Hey," "Dear," "Good day" or, when seasonally appropriate, "Season's greetings." To best select the appropriate greeting, determine first whether the letter is of a business or personal nature.
Business letters are formal in structure; the correct salutation for a business correspondence is, "Dear" followed by a colon; for example, "Dear Mr. Stanley:".
Personal letters are not restricted to such formality and can begin with "Dear," "Good day," "Hey," "Season's greetings" or any other greeting that might be used when addressing the recipient of the letter in-person.
The salutation in a personal letter is followed by a comma; for example, "Good day John,".