Email hosts and integrations

Need to switch email hosting provider. Can't be Google. Wondering about experiences with compatibility between scheduling/email campaigns/other integrations with particular email hosting providers (Apple iCloud+; ProtonMail; RackSpace; other???) Any tips or caveats? Stories of glory or horrible warnings?? Thnx

If you have iCloud+ you can have a domain email. I do it for my design site since I don't need workspace for it. Here's their support document on it. Might be helpful. https://support.apple.com/en-us/HT212514 It was super simple to set up and it works great with Campaigns.