<p>They can be sent by mail to the applicable office of admissions (sometimes called something else like office of registrar) of any college. Any letter needs to identify you as an applicant and your high school, and, if you have common name that many have, such as John Smith, it may also need to mention your address to assure it is matched to your admission file. The teachers should either send the letters directly to the college or give them to a school counselor who then sends then.</p>
<p>For everything my son had sent by mail he had the teacher make sure his name, dater of birth, and city/state of residence in the upper right hand corner of each and every page.</p>
<p>My son applied a couple years ago so I could be remembering wrong or it may have changed, but at that time you filled in the names & email of the teachers writing you letters. Common App then sent an email to the teacher about writing you a letter, and I believe the teacher had to indicate if they were going to submit online or through mail. And yes, you give the teacher the teacher form and an addressed stamped envelop.</p>