ISPConfig uses user prefixes and not user suffixes, you can not change that but you can remove the user prefix to migrate the old usernames and then activate the user prefix again.
Sorry I did not understand this well.
When you say ISPConfig uses user prefixes, what does that mean?
Is there a way to do the change without forcing users to change their settings in outlook?
2. My server is an external server from my workplace (dedicated server) but in my ISP provider it's probably part of a net.
So what would be the best to avoid the shared IP message? Just remove all sites from httpd.conf and create them with ISPConfig?
I have seen that the sites are created in the following way:
a link is created as /home/nameofsite pointing at /home/webX where X is a number. There all the files and folders are created. Cannot we just have /home/nameofsite?