"I'd like to buy a stamp please." "Certainly Sir, one way or return?"

Two Way Stamps cover the cost of using the same envelope and the same stamp to reply to any correspondence. (with a new reply address of course)
-- xenzag, May 15 2015

The Envelope https://ecoenvelope...t/window-envelopes/
Two use envelope to go with the stamp. [MechE, May 15 2015]

Yes son, re-lick that envelope to grandma.
-- wjt, May 15 2015


I like this. It would motivate me to write more letters, and to write with a greater frequency, since I wouldn't have to scrounge around for stamps and addresses in my junk box. The more I think about it, the more I like this.+++
-- blissmiss, May 15 2015


And the people you pay your bills to could send you another one.
-- normzone, May 15 2015


It would be a money maker for the post office, since only a fraction of the return envelopes would actually get used. (Unlike postage paid, where the company is only billed if it is actually mailed).
-- MechE, May 15 2015


And the logical end of this idea is the Lifetime Stamp, which as long as it can be discerned as such may be used forever.
-- normzone, May 15 2015


Single, return, or Season?
-- Ling, May 16 2015


Stamps could be called Ping-Pong, Tennis, Echo, etc., and be illustrated accordingly.
-- cudgel, May 16 2015



random, halfbakery