Welcome email, with wrong address, not returned to me

I've had this happen a couple of times. I add in a new member, then go to send them a welcome email. It gets sent. I think everything is fine. Then a few days later I send them an email (from my own email address in gmail ) to confirm that they got it. and I get a message back saying this is a bad email address. So I re-examine it or call them to get the correct email address.

My question is why did the welcome email bad email address notification not get sent to me in the first place? I am the website administrator. My name and email address are set up in the "Administrator section" Did I not set something up correctly?

This is a source of some ongoing frustration for me.

I had the email system set up to test the deliverability of email addresses to check for bad emails and do a proper bounce.

However, for some obscure email systems that was providing some false positives, so I had to dumb it down to keep users happy.

Because of the wide variety of differences between different email systems, not everything works as well as I would like yet. Everyone treats email as if it is same regardless of email system, but it really is not.