Field testing iredmail on a self hosted FreeBSD. Will use an SMTP relay if I get rbl'd for low traffic. Iredmail does dkim and Dane and dmarc. No drive, photo album. Can find freebsd alternates, just not packaged. Good calendar and two good web email choices, amavis, spam assassin. It's a good package. Works on Linux and docker,and BSD jails. Bind9.16 for dns. Let's encrypt wildcard certs, nginx.
Icloud+ can do a single domain for $2 per user per month. Even for non apple users.
O365 family edition $128 can do it if you use godaddy, good amount of storage and 6 family members. Also fine for non windows people
Cloudflare have an email redirector on test, invite only and I haven't been invited.
As a Google1 subscriber I'm paying for extra storage on a normal Gmail, I could roll that cost into $6 per user per month but I'd have to prune users and do more aliases instead (I ran about 9 accounts on the domain to handle billing and shared music &c)
Fastmail is good. I have pobox.com too, same company now.
