Even Registered mail get lost all the time. And, if they arrive after their expiration date, will they still honor it? No one knows for sure.
Only thing that's 100% is cashing them IN PERSON which I'm glad I did especially in light of sportsbook shutting down operations, possibly for months.
As a former postal worker, I can assure you that registered mail rarely, if almost never gets lost !
3rd class junk gets there reliably enough, and nobody will miss if it gets misdelivered, poatalese for lost, USPS has never lost a piece of mail, ever !, Well maybe in that Hindenburg thing ?
First class mail (FCM) is pretty damn reliable.
Registered is signed for by everyone handling it, it's like a million to one that slips by
I've seen some weird shit at USPS, I've seen 20 year old letters encased in a plastic bodybag and stamped " found in supposedly empty equipment "
They use things called hampers that get stacked up, 3-4 high and might be stored for decades, then a stray piece of mail is found 15-30 years later and delivered, very rare, but it happens
Registered is extremely secure
I've held boxes of stamps worth like 50k+ destined for smaller offices and it was a change of hands signature thing Everytime it gets moved.
RM doesn't get lost