Edit: just realized you said US based. Tuta is not US based so that might not work for you. Sorry about that.
Tutanota (now just Tuta) allows you to use your domain. I use it, it doesn’t support external clients (Outlook, Thunderbird, etc.) but they do have Android, Linux, Windows (maybe Mac too) clients.
It’s also cheap.
I’ve been using it for a few years now, it works for me.
You can get a free account to check it out first and if you like it just upgrade to get the personal domain usage and increased storage limit.