ProtonMail doesn't support IMAP without running a background bridge/converter, only their HTTP API, so on mobile you have to use their firstparty app, not the native OS email client on the mobile device. this is fine.
however, their 1p email client doesn't let you sort a mailbox, or select multiple items and move them all to archive or a folder. unsorted, one by one. ugh.
@sneak go to settings and use IMAP(on desktop)
@Dashtop what settings? i'm talking about ios.
@sneak OK, on desktop you have to go to settings and turn on IMAP, then you can use it on iOS with any client
@sneak just go to the site and check for yourself