The US Postal Service defines what counts as a postmark, for the first time

The US Postal Service has added a new section to its rulebook, defining what a postmark is and how it is applied. This means customers can now get clear proof of when their mail was officially accepted by the Postal Service.

For decades, the definition of a postmark was left to interpretation, which created uncertainty in legal and financial matters where the mailing date is critical. This new rule clarifies what counts as official proof of mailing. It means fewer disputes over deadlines and more predictable outcomes for anyone relying on the mail for time-sensitive documents.