Originally Posted by
cjw2001
I suspect this may be related to the issuers ability to track the delivery with the post office. (I've seen status tracking with other issuers that shows they know when the post office has done the final delivery.) That combined with you either calling from your own phone (Caller ID match) or launching a known app they've already gotten enough info to know you received the card and all is well.
I suppose this makes the most sense. In most cases, USPS marking card as delivered, IMO, shouldn't really be enough for a bank security-wise, since most mailboxes are not locked and therefore open to mail theft. Even though Chase never sends their name on the return address on envelopes with cards in them, I've been with Chase long enough to know where the cards come from, and I'd be surprised if there aren't others with nefarious intentions that don't know that as well.