There are 3 Letter types: Formal, Semi-formal and Informal.
Paragraphing the Letter:
All the 3 letter types, should ideally have the following paragraphs:
Letter Salutation:
Formal Letters: You don't know the recipient's name (logically), whom you are writing to. Dear Sir/ Madam, - Yours faithfully,
Semi-formal Letters: You know the recipient mostly by name (logically). They may not be too close to you. Dear Mr Sam, - Yours sincerely, [or] Dear Ms. Sharon, - Yours sincerely,
Informal: You know the recipient personally. Dear Steve, - Best Regards,
Indenting: