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Postal Encyclopedia

Mail.dat

Mailing documentation file format

Postage, Permits & DocsUpdated 2026-07-24

A standardized file set used to submit commercial mailing documentation electronically to USPS.

Definition reviewed 2026-07-24. This is a plain-English Plavidian reference; for USPS terms, the Domestic Mail Manual is the authority. For your own job, the final mail class, postage, and preparation are confirmed after list processing and production review.

Related terms in Postage, Permits & Docs

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Ask Plavidian Expert for an answer based on the USPS Domestic Mail Manual, or send us the job and we'll confirm the preparation before you print.

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