OX Open-Xchange Alternatives

OX Open-Xchange

Open-Xchange Server 6 is the most advanced Linux based Groupware solution f.
Open-Xchange Server 6 is superior in the following areas:
• Open-Xchange Server 6 offers most comprehensive Groupware
functionality based on modern user interface technologies and includes
email, calendaring, contact management, intelligent document sharing,
“smart linking” and much more.
• The architecture is designed for deployment in the hosted market.
• The architecture is designed for enterprises market

Open-Xchange Server 6 was designed especially to fulfill the following
requirements each of which is crucial for deployment in integrated hosting and
enterprise infrastructures:
1. Scalability to millions of users
2. Multi Tenant / Multi Domain capabilities to serve hundreds of thousands
small customers with one large data center
3. Integration into existing hosting infrastructure and services to leverage
existing services and to integrate in the hosting company's business
processes
4. Integration into enterprise environments
5. Offer the necessary services and interfaces to integrate into an existing
data center for automated administration, deployment and monitoring
with 24/7 uptime 365 days a year

(from http://software.open-xchange.com/OX6/doc/whitepaper/OX-Hosted-Architecture.pdf )