...it took OP 8 months of "rolling the gacha" and waiting to get a clean IP; no mention of costs. Not really a solution in my book. If you're willing to wait 8 months for working email, I put it to you you're actually using some other provider for your life and the thing you are playing with is a toy.
I've been self-hosting my email for a pretty long time. I first started down the reputation rabbit hole when a provider decided to shut up shop after a decade of operation, causing me to lose my lovely fixed IP block with its decade-old clean rep. Waiting/playing around isn't really an option when your email is broken and you need it working /today/ because it's not a throwaway toy - your digital life is tied to it.
Still, as I said at the start, if you get lucky, awesome for you.