I’m not sure which category is best for this one. With the more recent versions of Mail In A Box, I’ve found that I don’t appear to need the Kopano add with Outlook in order to set up the account as an Exchange Activesync account. It now seems to work straight out of the box and also sync the calendars and contacts with Nextcloud. I’ve also found that in the Windows 10 built in mail app, setting up the account using the Office 365/Exchange account type also works, and syncs the built in Calendar and People Apps as well.
I don’t know what @JoshData thinks - whether this is now expected, but I thought I’d share my experience with these programs. I welcome anyone else’s thoughts as well.