A colleague asked me if it was possible for Dovecot to store messages in the
cloud.
Does he have a more specific description of what he wants than “in the cloud”, or does he just like using buzzwords? From a user perspective, I would say that Dovecot, or any other IMAP server, already stores messages “in the cloud”. They are on a remote server, accessible from any location by any device that has a functional IMAP client.