Have you considered using a full TLD and hosting and/or relaying through a reputable service. I've used mailgun and sendgrid both for moderate accounts for outbound email and didn't have any issues. There's also hosting options for mail ranging from fastmail, to google, MS and others.

In the end, TFA is from a subdomain that seems to have a lot of spam, and to avoid it may mean using A commercial option, if not a specific commercial option. It sucks.. but the mail relays I mention above are relatively cheap and easy to properly setup with limited issues on the other side.