[kreig]

I worked for a NACHA processing backend for some years, the mechanism of protecting overseas transactions from bad actors is usually based on sending additional information contained in the IAT transaction, which includes some extra data from both the origination and the receiver[1]. When the bank process it, it could either:

1) settle the transaction in the next few days (3 usually).

2) ask for additional information on the next few days.

3) deny (return) the transaction if it looks too suspicious according to the bank.

[1] https://www.nacha.org/system/files/2019-07/IAT-Specific-Data...