As per Lawkidunya, here below the main seven 7 parts in writing a letter
1.The Heading. The heading contains the return address with the date on the last line.
2.Recipient’s Address. This is the address you are sending your letter.
3.The Salutation.
4.The Body.
5.The Complimentary Close.
6.The Signature Line.
7.Enclosures.