On the plus side, this personal experience made me very adamant about protecting mistakenly-registered users at my employer. When we were planning to add logged in accounts to our service, the sales team (understandably!) wanted the signup process to be as frictionless as possible, and thought that new users should be able to start putting data into their account as soon as they registered. I insisted that we require email verification before allowing users to enter personal data. When I got resistance to my plan, I logged into my webmail and showed the team all the crazy email I got from people who’d mis-entered my address, and suddenly they understood. I wasn’t just inventing some bizarre, unlikely edge case: these things really happen, and often.
Edit: And as you might guess if you squint at my username, my name isn’t super common. It’s not unique on the planet, but it’s certainly not “Smith”. If I have to deal with all this, I bet the Smiths of the world find it nightmarish.