No issues. I only use custom domains for years to be independent and they support it. Also they have nice ways for kids accounts with moderation of what’s getting into your kid inbox.

Except of shit web design that i don’t use, all works just fine. IMAP, caldav and so on. I’m super happy.

Mailo.com. It’s ugly as 2005 websites but it just works. You get IMAP, family accounts. It’s just email. Old and reliable french company.