but the license the community edition uses means it cannot legally be used by businesses.
I don't think thats true. The server Core is GPL. The Web UI is licensed under CC BY-NC-SA 2.5 of which they say: "Open-Xchange interprets Noncommercial to mean all INTERNAL individual, not-for-profit and for-profit use. ". http://www.open-xchange.com/node/783
The definition of "Noncommercial" is still being debated and defined within the Creative Commons community. It is a very difficult concept to define because there are so many scenarios to be considered. Open-Xchange interprets Noncommercial to mean all INTERNAL individual, not-for-profit and for-profit use. EXTERNAL individual, not-for-profit and for-profit use such a resale, rent and lease as well as inclusion of the digital content in an advertising model is considered COMMERCIAL use and prohibited under our interpretation of the license. We view the performance of professional services as a NONCOMMERCIAL INTERNAL use of the digital content and it is allowed.