Well all I did was RTFM (read the frigging manual) and changed IMAP, SYSTEM, USER_INTERFACE and USER_PREFRENCES.
I have changed the IMAP file because it listed my server twice. Once as a domain and once as local. It's useless since I'll add another domain as an array if needed. So now I have a clean login interface without confusing other users.
The SYSTEM file modification helped me to remove the option to set/spoof a mail address. I don't want users to spoof mail and why the option is enabled by default is beyond me. Now they can change anything except their mail.
The other two options just helped me make some global tweaks for users (like how their dates show and stuff). It's not needed as each user can set this but it's good to give them some default options based on what they would use.