A standardized file set used to submit commercial mailing documentation electronically to USPS.
Mail.dat
Mailing documentation file format
Postage, Permits & Docs
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.
Need this applied to a real job?
Ask the Plavidian Mail Expert™ for an answer grounded in the USPS Domestic Mail Manual, or send us the job and we will confirm the preparation before you print.