Replication between two ISPCOnfig servers

[Otto Saayman]

Hello

I have set up two servers, one master and one slave, using ISPConfig. I 
have been using rsync to synchronise mails between the two machines, but 
this has some unstable results.

I had a look at setting up replication: http://wiki.dovecot.org/Replication

When I run the command, doveadm user '*', only two users are returned. 
So when I run this command: doveadm replicator replicate \* I get: 2 
users updated

I run this command:
     doveadm sync -u [e-mail address] tcp:[2nd/ slave dovecot server IP 
address]

Here I can input any valid e-mail address in the ISPConfig MySQL 
database and it works.

How do I tell the dovecote server to replicate all the users configured 
in the MySQL database it uses when it handles logins via POP/ IMAP, all 
of which is working fine?

Is there a command I need to run at a set interval via cron to 
synchronise the two machines' mailboxes, which are identical in every 
way except the mails the users' mailboxes contain?

OR

Is there a way that I can instruct the two machines to keep each other's 
user mailbox contents "up to date"?

The main idea is to have a hot backup of my "main" dovecot server and 
also to enable a lower mail priority for the second server so that mails 
are still received when the main server becomes busy, or is taken 
offline for some reason.

Any help, or link to a HOWTO would be appreciated.

-- 

Best Regards

Otto Saayman