A letter from an individual to a business dealing with business of a formal nature
A formal letter from a business to you that is typed on business letterhead
A letter written from you to a friend about a business deal that is written on lined paper
A letter to deal with business of a formal nature from you and written on lined paper
The writer chooses what punctuation would be used and when.
A colon is used after the salutation and a comma is used after the complimentary close
No punctuation is used after the salutation or complimentary close
No punctuation is used anywhere in the letter
The writer would like closer to a situation.
That there is something else besides the letter included in the envelope.
The typist name.
A document physically attached to the letter.
Here's an interesting quiz for you.