In some cases MantisBT is setup in a way, where it allows users
that already exists in a directory or another application to be
automatically authenticated and added to MantisBT. For example, a
company may setup their MantisBT installation in a way, where its staff
members that are already registered in their LDAP directory, should be
allowed to login into MantisBT with the same user name and password.
Another example, is where MantisBT is integrated into some content
management system, where it is desired to have a single registration and
single sign-on experience. In such scenarios, once a user logs in for
the first time, a user account is automatically created for them,
although the password verification is still done against LDAP or the
main users repository.