I might be one who Pinknoodle thinks as “postcard police” (which in my opinion does not sound very nice). But it’s just that for me it is very clear what a postcard is . I joined postcrossing to swap postcards, so I hope to receive such. Very simple.
If you like to send cut out greeting cards, why not join a swap or tag, where everyone sends these, so every one most likely is hoping to get this kind of thing in return.
So I would wait until finding postcards again, and only then send official cards. Or send them to someones who write in their profile they are fine with postcard size piece of something, but of course you can’t know what address you get, so it would be safer to rather join that tag.
In your profile you write about “lovely postcards”, so if you still send these greeting card parts, I would change the profile a little
Edit. Link to the start of the tag page.