A user reported that in some cases it was not possible to register new users with a suffix…
Thats why you can now change the configuration to ignore unregistered users.
If you want unregistered users to be renamed just set the value of rename_registered_users_only to anything not true. It is true by default.
You can find the module on GitHub, see github.com/Natenom/mumblemoderator-module-collection/tree/master/os-suffixes.