Series III · Card 4 of 21 · THE MAILING LIST
If you really are a law-abiding citizen with nothing to hide, then why don’t you always send your paper mail on postcards?
PHILIP ZIMMERMANN · WHY I WROTE PGP · 1991
Turn it over, answer, sign – free, no account.
Source
“Why I Wrote PGP”, June 1991 (updated 1999), section on envelopes
About the author
American cryptographer and creator of PGP, one of the most important tools in the history of public-key encryption.
The question on the back
How much of your communication is really a postcard?