By default, WS_FTP Server allows users to authenticate to hosts other than the default host by including the host separator and the host name with the username, such as username@hostname.
Usernames cannot include the host separator. If you wish to use a different host separator (so that usernames can match email address, for example), you must change the host separator.
To change the host separator:
Caution: If a username includes the character you specify as the host separator, that user will not be able to authenticate after you change the host separator.