Formal Letters:
* Comma: Use a comma after the salutation in a formal letter.
* Example: "Dear Mr. Smith,"
Informal Letters and Emails:
* Comma: You can use a comma after the salutation in an informal letter or email, but it's also acceptable to use a colon.
* Example: "Dear Sarah," or "Dear Sarah:"
Other Considerations:
* Memorandums and Business Letters: A colon is often preferred after the salutation in memorandums and some business letters.
* Example: "To: The Staff"
* Social Media Messages: You can use a comma or colon, but it's also acceptable to use no punctuation at all.
* Example: "Hey John!" or "Hey John"
Ultimately, the best punctuation choice depends on the context and your personal preference. However, using a comma is generally a safe and widely accepted option.