Which email, calendar and contacts server to use?

The goal is to have one computer act as the server for email, calendar and contact. This computer is also a Samba sever. Other computers on the local area network, and a Droid phone can access the email, calendar and appointments. The clients are capable of setting new appointments, sending email, and creating new contacts. The server has the ability to synchronize data between the server and client(s).

Note that it is possible to have the server located on a web host account, and thus operate in the cloud. Cloud capability would be optimal. However, cloud adds a level of complexity with security. Due to various local laws, all data stored on the cloud would have to be encrypted.

I’m not sure what program to use for this. Before I invest too much time, I wonder if anyone can suggest a solution.