Print-to-mail is a way to send paper mail without having to go to the post office. Instead of writing out a paper letter, typing it up, putting it in an envelope, and mailing it, you can print out a paper letter and it will be sent to the person or place you want it to go. First, you use a computer program to write the letter, then you print it out. The printed letter goes into a machine that puts it into an envelope and adds postage to it. Finally, the letter is sent out in the mail.