Apple’s iCloud+ plans (starting at $1/mo) include email hosting with custom domains. I moved my family to that a couple years ago and it’s been fine. See https://support.apple.com/en-us/HT212514

Everyone in my immediate family has 1 or more email addresses in our family domain, and I have a couple of fun/project domains their too, for $0.00 above what I was already paying for iCloud.