We are currently a ZCS NE customer running one server at our primary hosting office, but would like to setup a backup MX in our secondary office. Is it possible, or permitted under the license, to use Zimbra as a backup MX in the second site? I did set up a basic postfix MX host but within a few hours I was getting spammed heavily. Part of the reason to go with Zimbra was so that the spam/AV features were bundled in and managed, if I have to configure up and maintain those features in the backup MX, then I've gained nothing really.
Here's how I'm envisioning the setup going.
Primary MX host, all users and domains defined here.
Backup MX VM, no users defined here, but all domains defined. Relay MTA set to the primary MX.
Would that be a valid configuration? Would the mail sit on the backup while the primary is down/unavailable as it should?