Which anonymous onion mail service works for clearnet registration?

I want to register for a special service which is not perfectly clearnet, but it has a normal browser url. Services like onionmail or dnmx don't seem to work for that, proton.me would work but it does require second email confirmation or connection with phone nr. now. "Anonymous" mail services like Tutanota the same shit, they also block every incoming email for the first 48 hours now!

Which email service(s) are anonymous and still would work both for onions and clearnet registrations?

Would one of the many temp-email services be an option? I'm sure you can find one that works in tor browser and is accepted by the 'special service' you want to register. They will be able to read your e-mail and potentially hijack your account of course, but perhaps there's a way to protect from that such as using 2FA or changing the email afterwards. Your 'special service' could also eventually realize you registered with a dodgy email and ban you anyway :