It amazes me that people fall for shot-in-the-dark e-mail scams like this (they must, or scammers wouldn't still be doing them).
I mean, yeah, they have to get lucky to match your actual current circumstances (ie, you're really waiting for a USPS package right now, or you are a customer of the bank they randomly guessed when generating the scam message), but even if that occurs...
I'm just stunned that there are so many people out there who blindly go "oh yeah, it must be them, how else would they know?" and proceed straight to the scammer through that e-mail link to dump info (or unknowingly download malware). It's absolutely insane to me.
If it's really your company, then your thought process should be... thanks for the heads up, I'll just go to your actual official site that's in no way attached to this e-mail to check my account or tracking number or whatever.