Configuring a mailcow failover

Hello everybody,
first of all, I would like to express my appreciation for the effort the mailcow team has put into this product. I have only configured mail systems by hand so far and I couldn’t do it that nice looking and awesome as it has been done with mailcow.
But now my real question: How do I create an environment so that I can minimize downtime in an unforeseen event.
The update.sh is a quick script but what if something went wrong during the update or I had to do updates to the host. As long as the stack is down I won’t be able to receive emails or have the WebUI for the end-user. If my limited knowledge of docker is correct, simply copying the entire stack to a different machine won’t do it. Even if I had a 2nd machine with its own IP and redirected the user to that machine, things would become inconsistent pretty quickly because both machines would store a different version of the user’s mailbox.
I am eager to learn how such failover systems are done the right way or if mailcow is even made to support that.
Any information on how I create a more secure environment in terms of uptime is greatly appreciated.