Here is a quick update that is fortunately not entirely unique. The seller is a stand up guy and said he would make it right and send me another card from the series, which I am/was very appreciative of. I got a snail mail letter with a card in it from him a few days ago. It stated he had originally put the card inside an old envelope that had his pre-printed return address on it. Otherwise it was a blank and unused envelope, with the card in it and stuck inside the, now mauled, mailer above.
Well, he received the blank envelope with the card still in it in his regular mail several (now) days ago. It was delivered with no postage due or anything. Now the original card is back to me and all is well.
I had another situation, similar to this, happen many years ago. That incident is recounted here somewhere in the archives. Fact is stranger than fiction. And props go out to whatever postal employees made this recent card retrieval happen.*The card is undamaged too.
"They did good" on this one.