GLOSSARY
Proof of mailing
By Justin Winter · Updated August 28, 2026
Documentation that a piece of mail was handed to USPS on a given date — the sending half of the evidence, not the delivery half.
Proof of mailing is a category, not a single product. USPS sells several things that produce it, from a Certificate of Mailing at the low end to Certified and Registered Mail at the high end, and they differ in whether anything follows the piece afterwards.
It answers exactly one question: did the sender put this in the mail when they say they did? Anything about arrival is a separate service.
See also
- Certificate of Mailing — A USPS receipt proving you mailed a specific piece on a specific date. It does not track the piece and it does not prove delivery.
- Certified Mail — A USPS extra service that adds a dated mailing receipt and delivery tracking to a letter, with the delivery record kept by USPS.
- Proof of service — A legal filing stating that a party was properly notified — usually a sworn declaration, supported by mailing evidence rather than replaced by it.
Back to the full mail glossary.