The difference between email and real groupware like Lotus Notes, GroupWise, or Exchange is like night and day -- once you've found yourself in a situation where the group features are useful.
One of my personal beefs is that there is no good opensource groupware -- or at least there wasn't when this Scribble was first scribed. Things are improving, and the search continues...
Zimbra hosting - cheaper than Google Apps or Office 365 - www.mrmail.com
Mailcow - new to me docker SOGO system - haven't tried yet
Tags: group ware, email, mail, folders, shared, contacts, public folders, calendaring, scheduling