Again, we don't know what actually happened, but presumably they read what they sent over to him.

Then there is no issue. They received notification.

They did not receive notification under the hypothetical scenario I described (the hypothetical scenario where he doesn't tell the bank that he changed the contract).

So, they received the new text, read it, and accepted it, but they were never notified of the new text?

It seems like you are requiring some out-of-band signalling? What should the specs be for that other signalling mechanism?

Yes. Out of band signaling is required. Like saying in the email "I've changed the contract, here are the new terms."

I don't know of any banks that process CC contracts by email.

My guess is that he filled out the application forms, set the terms of the contract how he desired them, left a note on top of it all to the effect of, "BTW, I changed the terms, lol. You should probably read them.", stuffed it in an envelope and mailed it to the bank. A bank clerk probably received the envelope, looked to make sure the application form was filled out and the contract signed, then marked in the bank's database that the requisite documents had been received.

Okay. But that's not the scenario I outlined. I made it clear that my points were referring to the scenario I outlined.