Protonmail does not support IMAP, what they have is a program called Proton Bridge that locally decrypts you email then you can set it up so that your IMAP client then reads from Proton Bridge, giving you a seamless experience with one email client having access to all your email accounts.
Protonmail does not support IMAP, what they have is a program called Proton Bridge that locally decrypts you email then you can set it up so that your IMAP client then reads from Proton Bridge, giving you a seamless experience with one email client having access to all your email accounts.