[kuon]

> If I ever reach this level (still using my 2009 email address), I would just abandon this email address and start with a new one.

Actually I have a business and this email is on all paper documents since nearly 30 years.

> Interesting approach. Can you configure a low enough (try-again-in-X-seconds) value? Are you not worried that legitimate emails get dropped here? I imagine transactional emails to not try and resend later?

It is part of the SMTP standard, all legitimate mail server actually respect that. Also, if there is a false positive, the sender should get a report email back.