[mdb31]

I've hosted my own email since, at least 1993 (that's on the Internet: I was on UUCP at least some years prior to that).

If you have a static IPv4 in a range that is not actively hostile, and you have proper SFF/DMARC records, things should generally work out?

And otherwise, services like https://www.mailchannels.com/ should help? (Still, you will need proper SPF records.)

I've literally had a 95+% delivery rate from users in actual Lagos Nigeria using the strategy outlined above.