I'm so on the fence about setting up my own mail server, it would be a good exercise for me and a good learning curve, but I shy away for most of the reasons listed - also downtime, sys fails and backups - its probably gonna be far better for my sanity if i just go with proton mail for my needs. (work and play) - I feel i would only be asking for yet another computing problem to walk into my life, at exactly the time I won't be wanting it :)
I am so conservative with my setups now days, I just want 100% reliability - lots of backups, no over-clocking, server grade MBs, ECC ram, RAID 10 or 6 only, only essential (but very comprehensive) software installed, play is of course done only on VMs.
I still get downtime and have moments when having 2 near mirrored HW workstation setups (as well as mirrored servers) has been a total blessing!
Just feel email server would introduce more downtime into my life - or isp/Internet problems etc.
Ah well rant over... nothing constructive to add - sorry!