After, Will Smith (Steven Hiller) leaves Jasmine to go to the air force base, he is in the locker room and sees a letter sticking out of his locker. He asks his friend to "do the honors" of reading it. We clearly see on the envelope that the letter is addressed to Steven MILLER, not Hiller as he is referred to countless times in the movie.
Maybe you should look a little closer because it actually does say Hiller. If your DVD player has a zoom button, try it. It does say Hiller, but even if it didn't, how often have you gotten mail or anything where your name is misspelled, especially when Miller is slightly more common a last name than Hiller.