Stamp Giveaway Series 2 #20 [solved]

Rubens (Nicaragua souvenir sheet); Michelangelo (Hungary souvenir sheet); (Paraguay large set and 2 souvenir sheets)

What was the earliest advice given by the British Post Office in regard to security of the mail?

The winning response will be the first correct answer received at or before 10 AM, July 1, 2022, eastern US time. If no correct answer is received, the first response wins. My decision as to winner will be final. Giveaway is open to everyone who wishes to participate and multiple answers are allowed. Good luck to those who decide to participate.

Will

Always seal the envelope?

Write precise name and address on the envelop

While doing the reading for the previous question, I ran across a discussion of the unreliability of delivery because of thievery.  One way to protect your letter was to cut it in half, send the first half, wait for a confirmation, then send the second half.  If either of your pieces of mail were stolen, the thief only had half a letter. Presumably if you didn't get some return correspondence indicating success, you could start over.

waisaacs, you are on a 2-competition winning streak. Congratulations!

Everyone else, keep watching for more questions.

Will

Wow, thanks Will!  I seriously feel like I got a two for one, as I learned this answer while reading on last week's.  I swear I'm not a postal history expert!  (Retired physicist/computing guy, FWIW.)

Cheers,

Bill