At least last I checked they didn't have a protonmail-bridge equivalent for IMAP support, so you're locked into the web UI unfortunately. It might be that if yo

At least last I checked they didn't have a protonmail-bridge equivalent for IMAP support, so you're locked into the web UI unfortunately. It might be that if you value privacy the best choice at the moment is actually to pick a non-encrypted provider with a strong GDPR/deletion policy and IMAP pull everything and simply keep your account clean by purging the remote at all times.