Frequently Asked Question:
What is the difference between Media Mail and Library Mail?
Media Mail is the method most sellers will use for shipping books and other eligible media. For a complete list of eligible items, click here.
Library Mail, however, is a service for mailing items "on loan from or mailed between academic institutions, public libraries, museums, and other qualified organizations in 2 to 8 days. Content is limited to books, sound recordings, academic theses, and certain other items. Advertising restrictions apply. Each piece must show in the address or return address the name of a school or nonprofit organization." (USPS DMM 173.3)