I am planing the backup in this way.
Please let us know is this a good solution.
i created two zimra open source mail servers.
1.mail.example.com another backupmail.example.com
i am creating two account on mail.example.com per user.
firstname.lastname@example.org and email@example.com
I will forward all the incomming and outgoing mails from each account like
firstname.lastname@example.org to email@example.com account
I will create a account firstname.lastname@example.org on my another zimbra server.
Then i will add an external pop account in email@example.com to fetch mails from firstname.lastname@example.org
This backupmail.example.com i am planning to put in remote location with a vpn connection to mail.example.com server for fetching mails.
Please provide your valuable suggestion on this setup.