Wally wants to sell his used computer to Susan for $400. Susan says that she will think about it. Wally tells Susan on Monday that if she wants the computer, she must call him on his cell phone by 6 p.m., the next day. That next morning Susan decides she does want the computer, but she has misplaced Wally's cell phone number. She finds his address in an old campus directory. Therefore, she drops a note to him through the United States Postal Service telling him that she wants the computer. Meanwhile, on Wednesday, before he gets Susan's acceptance, Wally sells the computer to Alice. When Wally calls Susan to tell her the bad news, Susan tells Wally that she accepted the contract and that under the Mailbox Rule, he is liable to her for damages computed by the difference between $400 and the amount it costs her to obtain a similar computer. Who will win in the dispute between Wally and Susan and why?