Ok, so you really can't separate the web-client out of Zimbra and use it with another backend. However, Zimbra does use postfix
Originally Posted by Matts
With zimbra, an account is located on only one mailstore at a time; you can let it auto-spread out the collection of new accounts across all the mailstores, or manually assign everyone in one domain to only be stored on a particular mailstore:
(just assign a different COS per domain)
You can deploy a load balancer for the Zimbra server so that all users can log in using the same address/name instead of having to remember which server their mailbox is on.
So you'd set up a virtual hostname of mail.example.com and configure three mail servers, mail1.example.com to mail3.example.com.
When users log on to mail.example.com, the load balancer directs the user to any one of the mail servers to verify the log on information. After successfully logging on, users are redirected to the actual server their mail is stored on.
(Thus, while they are logged on, all subsequent requests can go directly to their assigned server.)
In order to configure load balancing for ZCS:
1. Each Zimbra servers must have a routeable address/name.
2. You must configure the virtual hostname on the administration console.
3. You must turn on the following localconfig setting on each mail server:
So here's an example:
zmlocalconfig -e zimbra_auth_always_send_refer=true