I’m reading the recent release from from US Treasury regarding paper checks being mailed that are post dated. Has anyone ran across this?
ICBA is saying that banks are not expected to return the checks but additional guidance is forthcoming.

ICBA post dated stimulus checks
Dept of Treas notification

We started receiving them yesterday. We had several presented.

Here's another thread on this issue:
https://www.bankersonline.com/forum/ubbthreads.php/topics/2235423

Back before the SSA phased out all but a few Social Security payments by check, and everyone was paid at the same time, Post Offices all over the country received trays and trays full of checks post-dated to the third of the month. The deal used to be that the local PO held them until the third (or the Friday before if the third was on a weekend). Sometimes those checks would show up at banks before their check dates.

I was surprised when a search of the Fiscal Service's website showed no references to post-dated T-checks.

I'm betting someone at Treasury or the Fed (maybe Mnuchin himself) will fire off a statement saying these checks (and others to come that will also likely be post-dated) should be accepted, will be paid, and won't be returned except for fraud.