I can recommend https://mykolab.com/ https://mykolab.com/ based on Kolab (http://kolab.org/ http://kolab.org/). They value your security and privacy highly. Th

I can recommend https://mykolab.com/ https://mykolab.com/ based on Kolab (http://kolab.org/ http://kolab.org/). They value your security and privacy highly. The data is hosted in Switzerland. Also you can have groupware features like calendar and address book with open and standard interfaces like CalDav and CardDav.