I tried this for a little while but quickly stopped as a critical mass of websites broke when I tried using it to sign in. Special characters in your email address is an edge case that produces inconsistent results even within a single product

YMMV, I think I only tried to sign up on 3 websites where it was not working. You can fallback to the original email address in those case.

The funniest part was that for one it work great for the signup part, but they used a third party tool for licences that broke because of my e-mail. For another, only the js code was verifying the e-mail, and I could push it by removing the validation. When the owner had to validate my account, they got a message that the e-mail was incorrect when they tried to submit the form. They called me and had a great discussion about web apps security. We had a good time.

I would point out that it kind of prevents you from checking if your email is in a leak database as you need to test each aliases you used.