The US Postal Service clarifies what a postmark means, and what it doesn't

The US Postal Service wants to add a new section to its rulebook defining what a postmark is and when it applies. This new rule will clarify that a postmark proves the Postal Service had a mailpiece on a certain date, but not necessarily the exact date it first received it.

For decades, the postmark has been a simple, universally understood legal fact: the date the mail was sent. This proposed rule introduces a subtle but important distinction, separating the date the postmark was applied from the date the mail was first received. This could create new legal arguments about when something was officially 'sent' or 'received,' especially for time-sensitive documents like tax filings or legal notices.