Your 1-3 are why I never enable automated e-mails in the first place. E-mail automation is an atrocious idea. If you ever get on a blacklist, it will take years and most likely some de facto bribes to clear a domain. That's probably why 99% use google, aws, and other centralized billionaire mail services that cannot lose rank due to being the dictator.
Instead of contributing to an ever more bizarre dystopia, how about we scrap greedy 3rd party data-krakens, and do what has been done since phpBB v1: homemade, creative CAPTCHAs? Offline, no cloud bs, user-friendly. Bonus points for making them keyboard/screen-reader friendly.
Everything can be botted, but having a variety of random ones surely stops 95%, because it's too annoying, and the mass bot crap is not targeted.
It could even be a community 'thing' to come up with new, fun ones.
Other than that, manual user creation after manual verification by mail makes sense to me. A BB is not meant to be real-time, zero-attention-span anyway. Genuine users can wait a day or two for a new account. I've asked how to do so here .
