Funnily enough Roundcube isn't even one of the mail protocols. Its software connecting to the mail servers via a GUI over HTTP(S). You don't have to give the e

Funnily enough Roundcube isn't even one of the mail protocols. Its software connecting to the mail servers via a GUI over HTTP(S). You don't have to give the entire world access to your web server. You could even use something like AuthPF to allow yourself to access it. Or a VPN like Wireguard. I do the latter now, but I used to do the former. Although back then I just used Mutt over SSH usually. Way faster than the web software I ran back then (probably Apache with Horde). What remains is all the stuff required for sending and receiving email. SMTP, IMAP, and the stuff to deal with spam (some kind of tarpitting as well as SPF/DKIM). In fact even the IMAP server could run behind Wireguard. So its only SMTPd and SPF/DKIM. There are some very secure SMTPd written, with great track records. Back in the days I ran Qmail with Courier-IMAP but I don't think SPF and DKIM existed back then.