We require an Open Source eMail System configured as Primary System with Failover to Secondary System which uses a Shared Standard Type Database to ensure continous service and ease of Import/export of emails. The Primary & Secondary systems need to be able to run on Virtual Servers on Vmware ESXi Server. We are currently using the Zimbra Email system with IMAP and need to Export all emails to the new system. There are approximately 50 email accounts to migrate. We require an Estimate for Time & Cost.