sent email delivery delayed?

sent email delivery delayed?

I sent an email to a prospective client yesterday and I received this message:

Delivery is delayed to these recipients or groups:

This message hasn't been delivered yet. Delivery will continue to be attempted.

The server will keep trying to deliver this message for the next 1 days, 19 hours and 59 minutes. You'll be notified if the message can't be delivered by that time.

Can I be assured that if this message doesn't get delivered that I will be notified? This email is critical. I can resend it, but I don't want to be redundant. I just want to be certain that the system will indeed notify me if it doesn't get delivered.

By the way, is there any way to know if something has been delivered?

Thank you!
Elisa