From Zarafa wiki
I have more than 15 years experience in high availibility on UNIX. My favorite OSses are Solaris and Debian Linux. My Zarafa experience is longer than two years, even if I start to use zarafa commercially right now.
Located in Germany, I run my own business (www.itserv.de), where I give work to fifteen employees. Our customers are typically large companies which operate their own data centers.