I felt compelled to share this. Some of my international mail was returned to me (wrong address, person moved, etc.). And it is fascinating.
I got some mail returned from Ireland. And it has Irish Gaelic on it. Irish Gaelic!
I’m sure its actual collector value is probably low. But I’m still going to hold onto it. It looks fascinating. 
This, I understand. I bought a set of oddly-shaped coins of the world at a flea market for two dollars. I’m sure that the value of the coins is less than that. But, they are very neat AND they are proof that coins don’t need to be round.
To ensure that one gets attention for one’s theories, consider mailing them as packages, not envelopes.
It’s probably also a good way to meet all kinds of interesting people - postal inspectors, Homeland Security, ATF agents…
Unlike Tuits.
A round Tuit is a necessary item in the interactive fiction game Eric The Unready (from the guy who brought you Spellcasting 101-Sorcerers Get All The Girls and Superhero League Of Hoboken).
Nice. I’m positive the Post Office stole my package because it didn’t have enough postage.
Probably related this before in some other thread. Back in the 80s my wife got involved in politics, we were helping out a couple of candidates in elections and my wife became Democratic Party district leader. We were warned and the warnings came true, mail started getting delayed, letters were opened, often mangled to provide an excuse to open them. It was a tiny post office, maybe only 4 full time employees at the time. We got profusive apologies and phony excuses about the delays, mangled and opened letters but it did stop.
Maybe if they stole half the contents, it would then have enough postage?
It can be a scam to mail something for free or with incomplete postage so the letter gets ‘returned’ to the return address which was really the destination. That probably pisses them off even if done mistakenly.
@Jackmannii Funny joke. I suppose. But on a more serious note, as I’ve said many times before, I’ve done nothing inappropriate or illegal. 
What you have done is to confuse the issues of legality and appropriateness. You seem to have little insight into the latter. Your persistent unsolicited letters to scientists are certainly not appropriate. If they were good ideas, people would pay attention without being spammed.
I thought of The Bad Seed.
I just got some mangled class action settlement in a ‘We Care’ envelope from the USPS; probably 1/3 missing, & when I took it out & opened it up it looked like a shark enjoyed it
The only hand addressed mail I get is some type of (holiday) card, a party/wedding invite, or something from the JWs. The latter is always from a somewhat local address with a name that I don’t recognize. I open it long enough to see it’s handwritten on a piece of notebook paper & from there it immediately goes into the recycle bin. I couldn’t even comment on the penmanship because I don’t get that far; I’m really amazed at how many of you actually read them before throwing their letters out.
Did any of those phony printed to look like handwritten letters from local realtors, roofers, or window salesman ever get damaged in handling and delivered like that? I kind of doubt it.
And yesterday I got a letter returned from Russia. Russia! I’m definitely going to hold onto that one too.
And the return label is written in Cyrillic. I can’t read Cyrillic.
But it also is written in French. It says ‘non réclamé’. What on earth does that mean?
Googling, that means “unclaimed”.