Not sure this qualifies since my sent postcard made it to the destination.
However, it arrived with another card stuck to it, traveling & hanging on from Florida to Germany.
We both hope that all worked out for the intended recipient.
Fun side note: I also included a spider stamp on the postcard and the day before it arrived, the recipient was offered a PhD study in spiders! (No mention of spiders in his profile - my selection was based on his love of art & music. The art is a tribute to David Bowie.)
I sent a cover to Brunei in July 2021, and it was returned last week with postal marks saying “Missent to Nicaragua”. Apparently, the post office in Managua was not able to send it on to Brunei, and simply returned it to the US. Next time, I’ll add “Asia” or Borneo to clarify where Brunei is!
Interestingly I received a card yesterday (19.02.22) from (stamped on the wrong side with date 16.02.22) … but with a stamp “Missent Tokelau” … Quite amazing considering the distances …
Considering even I, involved in international shipping and therefore quite good at geography, had to look up Tokelau’s location, isn’t it weird that a card is missent THERE? And from what I see here it’s not the first time that happened.
Omg!! That’s so interesting! What does the address say? Especially the country name… Maybe it was written in a way that made it look like “Tokelau”… “Duitsland”, if written quickly, could resemble “Tokelau”? Haha maybe that’s too much of a stretch!
EDIT: Ok since all these cards come from a Dutch user (and I’m certain it’s the same person), then I guess it’s a fake missent stamp. Especially given how they’ve sent stuff from the UK and from Germany as well. Not cool!
I recently received a card from the Philippines that was travelling for over 6 months. Looks like it took a detour to somewhere that speaks Korean (South Korea maybe?) where a post office oddly thought there was an ‘insufficient address’. Though the address is complete. What a journey!
I’ve now joined the missent card club. This one was sent from Sri Lanka on Aug 15 and just arrived in Canada on Sep 20. I was surprised to see that it happens so often they have a stamp for it. Glad the card finally arrived!
One of the funniest missent stories happened to me one of my first years on Postcrossing, with a private swap : I sent a card from Genoa (Italy) to Venezia (Italy), with the correct zip code, initials of the province, stamp for national mail and everything. It took more the one month to arrive, and then it had a mark saying it was missent to Venice (Florida, Usa)
If you look at @Ehsan 's received postcards, he was sent three from the US on 16 August, plus others in the spring. Has the ban been imposed after 16 August?
(stamped on the wrong side with date 16.02.22) … but with a stamp “Missent Tokelau” … Quite amazing considering the distances … 
Strange idea of fun, then …
, Matildasha, for mentioning it to me.