Any providers that don't provide SMTP/IMAP/JMAP are just a boring way of giving away control over your mail and the client software you use. I don't know about

Any providers that don't provide SMTP/IMAP/JMAP are just a boring way of giving away control over your mail and the client software you use. I don't know about Tuta specifically, but Protonmail is practically intentionally hostile against anyone using their own keys. Which is the biggest sign that their marketing and actual intent do not align.