Mail Server High Availability

I’m looking for a solution to increase the availability of my UCS Mail Server. I read this post about High Availability but I don’t know how to configure an SMTP Proxy Server with UCS.
I already implemented HA solutions for LDAP, Samba AD, Kerberos, DNS and DHCP, but now I need to know how to proceed to implement an SMTP Proxy server that can cache mails during UCS main mail server downtime.
Do I need to install Mail Server on another UCS Server?
Is it enough standard Postfix installation?
I searched on UCS documentation but I didn’t find anything about that.
Could someone help me?


a setup with a normal SMTP Proxy to cache mails during non availability of the “main” mail server could be realized with an UCS Slave with the mail app and some configuration of postfix. At the moment there doesn’t exist a How-to or documentation for this.

Some hints:


Thanks Tobi for your reply, I decided to proceed with the installation of a new UCS Slave with Mail App.
Could you or someone else give me some more information about what I need to change in Postfix configuration in order to cache mails during downtime of the main mail server?
It will be very helpful a document, maybe we can make together some basic information on how to do this configuration.

It’s also very interesting your advice to setup two identically constructed mail server with a shared storage, but I have a working UCS Mail Server with a lot od mailboxes and in this moment I don’t want to move to a shared storage, I’m only looking for a temporary solution for short downtime.