Indication that something needs to be mailed

(See Seal, Cauterize)

A postage stamp put on a letter may point to the cost or value of the message sent or received in a dream. It may represent the payment of dues.

Literal, though timing may be elusive

The amount may be symbolic, but it will be a true indication of value; research details

(See Ring, Seal)

Putting your stamp on something. Desiring a higher position.

It is a sign of remunerative activities to dream of collecting postage stamps as a hobby.

interpreted upon 5 sides: high rank, high standing, preservation / saving of something & collecting of wealth, blessing.