Yeah, email is one of the more annoying things to self host. Google rejects mine because my ISP has all their non static IPs on block lists (even though my IP hasn't changed once since I've been with them it's still not "static", can't change the reverse DNS) and I'm not paying 150% more a month for a business account to get a static IP. I ended up just using a free email relay. Still had to setup SPF, DKIM, DMARC, and all that jazz still.