If you are using a global user directory (LDAP, Active Directory), you may want to configure MantisBT so users who already exists in the directory will 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 option could be if 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.