This makes me 😭
UPDATE: Thanks @nekusoul@lemmy.nekusoul.de for this update: The issue has now been commented on and was closed by the maintainer, where they explained why those blocks would be nonsense. But it appears the OP wants to still talk with maintainer privately about it.
This happens to me occasionally already as a paid Fastmail user. I switched from Gmail about a year ago and I can’t change my existing Yahoo account to use Fastmail.
I get it, we deal with fraud and abuse from throwaway emails all day at work, but it is frustrating for sure.