I don't think that it's something you know, (the last 4 of your credit card or social security are used for that).
My guess is that they have different email campaigns tied to your bank account, credit card or investment account, etc. This is probably the only way to make sure you don't get any emails from that account.
My guess is that they have different email campaigns tied to your bank account, credit card or investment account, etc. This is probably the only way to make sure you don't get any emails from that account.