I have a Virtual Server with some email users that I can access with Usermin.
The owner user also accesses both Virtualmin and his mailbox with Usermin.
If I install the Roundcube script, this error appears.
What I notice is that @localhost is being searched for.
If the error refers to the contents of the /etc/hosts file, localhost is a different domain than the one used for mailboxes.
Server = hostname.domain1.tld1
Virtual Server domain = domain2.tld2
I didn’t make a snippet; what I posted is all that appeared.
I have already read the documentation and continue to read it now.
I can’t find anything that can help me figure out where the problems are with the scripts.
Instead, I have the doubt that the origin of all my problems is having Virtualmin associated with a domain that is not used in the Virtual Servers.
I wonder if all the various problems reported by me do not depend on a bad initial configuration.
The server (with Virtualmin Pro) has an FQDN resolved from an A record in domain1. This domain is in a DNS zone managed by the provider.
In Virtualmin there are two Virtual Servers that resolve Domain2 and Domain3. These domains are managed by Virtualmin which acts as a name server.
As most of us have found the scripts actually work (so no problem with the scripts) I have installed Roundcube on 5 VMs all without a problem.
Given some of the similar problems you have reported (re phpMyAdmin - another script that installs well) I also get the impression this is not a typical Virtualmin installation)
The op has changed the mysql password to something else so the domain owner and mysql passwords are different, that said the OP may have reverted back idk
