postal note

noun3

1. •
   (historical) A note of postal currency.

   • Since no two things are alike... there must be a difference between two postal notes. — 1862
2. •
   (US, historical) A fixed-sum postal order issued by the USPS between 1945 and 1951.
3. •
   (Australia, New-Zealand) Synonym of postal order.

   • In 1893 an inland and intercolonial parcels post was established and the postal-note system introduced [to New South Wales]. — 1926