UM
The dual license open-xchange means you can't provide a paid for service using the free version, does this mean Dovecot and PowerDNS will go that way too?
Open-Xchange, a maker of web apps that some of the biggest telcos and hosts rebrand as their own, has bought up open-source mailserver firm Dovecot and DNS server outfit PowerDNS. There are lots of possible reasons for this burst of activity, the most obvious being Open-Xchange's desire to offer its service provider customers …
https://www.suse.com/company/press/2002/10/openexchange.html
First time I heard of OpenExchange was in 2002 - I tried it back then and it was pretty impressive stuff.
I imagine it is much better now.
From what I saw it had email, calendering, and various other productivity functionality ... this was in 2002. It was, at the time, way ahead of what OWA 2010 is now.