Running an email server is kinda bullshit though cause of all the SPF and DKIM DNS stuff, DMARC reports you gotta keep up with, plus they gotta have static WAN IP, and will start with low reputation score so Gmail et al will filter messages until enough recipients tell them its not spam.
But if like a steep learning curve and lots of maintenance then go for it. (I use mailcow dockerized in a VM on my local on prem server)