Here's my simple backup plan

Primary
zimbra.domain.com
192.168.1.100

zimbra.domain.com
192.168.1.101

I setup a cron job on every midnight...

Code:
service zimbra stop

ssh user@192.168.1.101 service zimbra stop

rsync --delete -avh --progress -e ssh /opt/zimbra inet@192.168.1.123:/opt/zimbra > rsynclog

service zimbra start

ssh user@192.168.1.101 service zimbra start
So once the primary is down I can switch the smtp and pop to backup and have all the setup in backup server.

Will this work? and what are the things additionally I need to do?