Lawyers at the Coollawyer.com, explain the legal "paradox" inherent in the LOI, wherein the signing of an LOI, is often prone, not to bringing about less litigation, but more litigation, and put it this way:
At the end you should sign off with "sincerely yours" or any other related salutation. If you are writing a letter of intent for graduate school then it would have a different content. First of all letter of intent would start with your name, address, contact number and email address. After you have mentioned the date, you should then add a salutation like "Dear Sir/Mam".