You can set up a free Yahoo mail account and get real-time e-mail delivery, also known as "push e-mail". This means that when you get a new message, it will show up on your iPhone as it arrives. There is nothing you have to do to set up this feature-it is done automatically. You'll know that you have new mail by glancing at the Mail icon on your Home screen to see if there is a circled number in the upper-right corner, indicating how many new messages you have waiting. You'll also hear the "You've got mail" sound.