"T-2 Days Until The Wedding And I Just Got This In The Mail"

"After a very emotionally and financially taxing wedding planning era, I felt I was finally turning the corner today into excitement for our wedding on Saturday when I recieved this letter in the mail, no return address and no real discernable information for who may have sent it. The only clue is on the postage cancelation stamp, I can deduce it came from a post office not far from my hometown but in a populated area from which a lot of our guests hail from, and about an hour from where we live. It was addressed only to me (bride) and not my fiancé. I have been wracking my brain for who could have possibly sent it but am coming up short. Any advice on how to not spiral??"
Society was much better before the Smartphone.
And the advent of social media.