Some things cannot be mailed or can be mailed only in small quantities for safety and legal reasons. Also, some items can jam or damage the mailing machines and can cause serious injury to the Mail Center employees and equipment. The U.S. Postal Service lists the following items:
Flammable or explosive materials
Illegal or infectious substances
Envelopes and cards less than 3-1/2" in height or 5" in length are also classified as non-mailables and may be returned to sender. Also, all foreign countries impose various restrictions. It is recommended that when mailing questionable items to U.S. or foreign destinations, the sender should call the Mail Service Center at ext. 6292 or Student Mail Center at ext. 2707 for assistance.