Why were compensatory payments created for countries receiving much more international mail than they send?

The international postal system traditionally operates on the principle that each country retains the postage it collects on international mail, under the assumption that every letter sent will generate a reply. This approach was designed to simplify international accounting by eliminating the need to share revenue for each item delivered.1

However, this rule created a significant disadvantage for certain developing countries that experience a substantial imbalance in their mail volume, where they receive far more international mail than they send. Because the receiving country does not collect postage for incoming mail, these nations were effectively subsidizing the delivery costs for other countries' correspondence. To address this financial inequity, the 1969 Congress of Tokyo introduced compensatory payments, allowing these countries to receive financial adjustments for the excessive volume of incoming international mail they process.1