10 self-service mailing and printing tools, free — create a no-cost account to try them now Try the free tools Request a Quote
PlavidianOrder, proof, track, and manage your print and mail projects online.

Postal Encyclopedia

Mailer ID

Updated 2026-07-24

MID

Barcodes & Tracking

A USPS-issued number used in Intelligent Mail barcodes and electronic documentation to identify the mailer or mail owner.

Definition reviewed 2026-07-24. Plavidian reference, written from the USPS Domestic Mail Manual. Final mail classification, postage, and preparation are confirmed after list processing and production review.

Related terms in Barcodes & Tracking

Need this applied to a real job?

Ask Plavidian™ for an answer grounded in the USPS Domestic Mail Manual, or send us the job and we will confirm the preparation before you print.

Ask Plavidian Request a quote