Namecheap Private Email
(powered by Open-Xchange) is a cloud-based open-source collaboration software that meets all necessary email, calendar and contacts, tasks management and document storage needs.
Namecheap Private Email Business packages will enable you to do such things as: create a public space in shared folders; set and control tasks; create and manage work schedules; monitor the availability of colleagues for participating in meetings/discussions; share data: control who has access to specific files etc.
Namecheap Private Email also provides social networking capabilities, enabling automated publish and subscribe capabilities between instances of Namecheap Private Email Server and social networking sites like Facebook, and various Google services.
Thus, Namecheap Private Email is a great choice for organizations and optimization of teamwork.
Namecheap Private Email User Guide can be found here