Many a time, especially in a case involving a supposed seller who is either a fake seller or does not actually have the supposed crude in hand yet, or, an unscrupulous aspiring seller's agent or broker who actually has not acquired a crude supplier (seller) yet, buyers may issue an LOI only to find out that there is no seller on the other end. This happens a lot in situations where you have an hungry agent or facilitator who is still struggling to get a real supplier, and by extracting this LOI from an unsuspecting buyer, this facilitator can commit the buyer only for him then to start hustling to find a seller or supplier.
In the body paragraph you will basically express your interest in taking admission. Important things you are going to mention include the basis for applying to the school. Why do you think this school can build up your career? List down all academic achievements and special skills that would help in making your letter stand out from rest of the applicants.