I also haven't read through the entire thread, but....
I mailed a $50 Applebees gift card in a Christmas card to my accountant and he only received the battered front part of the envelope. No card or gift card. I called the Applebees number on the back of another card I purchased and they said the card was redeemed in the town of the sorting facility 3 hours away from me and 1 hour away from my accountant.
I will never again mail a gift card in the mail in a regular envelope. Instead I will send it in a cardboard envelope if I send it at all. I've never had an issue like this before. Clearly a disgruntled postal worker decided they needed that meal more than my accountant did. Some people are such jerks!!