Recently found this while looking for a decent cloud provider to get away one drive. The monthy price varies for people with share in nubo and the ones that don’t have the shares. Usually the price starts from 3,5 € for 5 gigs. This can be used as a alternative to google’s gmail and drive.
Looks like they use Roundcube for the email client and Nextcloud for the storage part, with calendar, contacts etc.