Treasury's requirement that you provide 30 days' notice applies only to accounts received a federal benefit payment. I imagine that the direct deposits from the USPS are salary payments and not benefits payments, so you can do whatever your deposit agreement says you'll do. Or, since kiting is a form of fraud, and could cause the bank a loss if you don't act swiftly, you can provide no notice at all (or very short notice if you can't stand the idea of closing without notice).
Be aware, though, that your state may have something to say about a notice period for account closings by the bank.
John S. Burnett
Fighting for Compliance since 1976
Bankers' Threads User #8