What no-one tells you about changing servers
I had real grief changing to a new server for Scalix. I tried lots of ways and wasted time (especially as my mailstore is 26GB). The way I found is as follows and works painlessly:
Source: RedHat ES3, Scalix 11.0.4 Dest: CentOS 5, Scalix 11.1
I was keeping the domain name and hence set the new server to the same hostname as the old one. I understand that changing the domain or hostname is a serious problem. I did however change the IP which seemed to cause no problems (with a note below).
Start with a completely clean install of Scalix. DO NOT start by copying your mailstore as I did expecting the installer to upgrade it. You will cry!
Rename the mailstore directory /var/opt/scalix/xx and then replace it with the mailstore from your old server.
(Important!) Make sure that the old uid/gid of the scalix user on the old server matches the one on the new server.
Now the magic bit no-one told me: run ompatchom - this upgrades your old mailstore.
Restart Scalix and all should be fine! (Well it was for me)
I noticed that the indexes include the server IP so you probably should reindex the mailstore as well. See HowTos/RebuildiIndex in this WIKI.