[aasasd]

That's far from the only thing smuggled into space, so dunno if there's something special about ‘postal covers’ (whatever that is).

Here's just a partial list: https://en.wikipedia.org/wiki/List_of_items_smuggled_into_sp...

Even Apollo 15 seems to have had another unlisted item, an aluminum figurine: https://newatlas.com/things-smuggled-space/45285/

[jjw1414]

Interesting list. I wouldn't be too fond of my Gemini crew mate who brought the corned beef sandwich.

What was special about the Apollo 15 postal covers, and relevant to the OP, was that the crew accepted monetary compensation to transport them without informing NASA officials. This was where the legality debate came into play.

As for "postal covers" [1], I had to look it up, too. I always thought that they brought collectable stamps.

[1] "essentially envelopes with printed decorative cachets". http://www.spaceflownartifacts.com/flown_apollo_covers.html