Before postage stamps who paid for the mail to be delivered?

In some jurisdictions (parts of the world), it was the sender, whilst in others, the onus fell on the recipient.

Given that postage stamps originated in Victorian England (c. 1840), that will be the focus of this answer. In those times, before postage stamps, it was the recipient who paid, but that caused a significant problem:

...the costs of delivering mail were not recoverable by the postal service when recipients were unable or unwilling to pay for delivered items, and senders had no incentive to restrict the number, size, or weight of items sent, whether or not they would ultimately be paid for.

https://en.wikipedia.org/wiki/Postage_stamp

Postage stamps solved those issues by requiring senders to pay in advance.