You can mail books back to AU:
To avoid fines, first renew your books online. Books from the general collections of the main libraries of WRLC may be renewed online through your library account portal.
Before mailing the items, it is a good idea to email the Circulation Department and let them know to expect your package:
circulation@american.edu.
Please pack the books carefully, consider insuring the package, and send them to this exact address:
ATTENTION: CIRCULATION
Bender Library
American University
4400 Massachusetts Ave. NW
Washington, DC 20016
If you have questions, call Circulation at 202 885-3221 or send them an email.