When this field is set to Yes (as it is by default), all mail / FTP users will have their usernames forced to lower case, regardless of what case they are created in. If you want to prevent this behaviour, select No to have mailboxes created with the exact case entered. Be aware that for logging into Usermin and any POP3, IMAP or FTP server, the correct case must be used.

Because most mail servers cannot handle delivery to users with non-lowercase names, this option should always be left set to Yes unless you are creating accounts for FTP, DAV or SVN use.