I meant IMAP, SMTP, POP3. It’s true that they do some encryption shenanigans, but firstly I don’t really see the benefit over just using encrypted SMTP and encrypted IMAP, and secondly we already have PGP for that, IMO it would be better if they made that more accessible.
Some people might not be bothered by this, but it bothers me a lot. Which is why I left. The reduction of usability is not tolerable.
Besides that, they also don’t support CalDAV and CardDAV (syncing of contacts and calendar), which is something that groupware absolutely needs to be viable for me.
You might disagree or not care, if so, good for you, there is definitely much worse than proton.