A mortgage payoff letter can come in two forms. One form tells borrowers the remaining principal amount and interest they have to pay to close out the loan.Payoffs must be made via certified funds—wire transfer, money order, or cashier's check. Please do not send personal checks, certified personal checks, or cash. San Antonio, TX 78269-2408. Or Fax to (866) 493-1441. San Antonio area: 210-200-6770. Outside of these areas: 800-346-5312. Main Line: (210) 736-7600. Jeff Line: (833) JEFF LINE or (833) 533-3546.