My understanding is that USPS only delivers Amazon Prime orders on Sunday exclusively due to a special contract with them and FedEx.
"Regular" mail and USPS packages are not delivered on Sundays.

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When in doubt, WHACK the GAS and DITCH the brake !!!

Yes, there is such a thing as NORMAL, if you have to ask what is "NORMAL" , you probably aren't !
Failure may not be an OPTION, but it is ALWAYS a POSSIBILITY.
ALL systems are GO for MAYHEM, CHAOS, and HAVOC !