{1}Trusted Mail Domain Settings{2} is a way to specify the mail servers used for user self-registration.{0}You can either to check the {1}Custom domains{2} option and enter the trusted mail server in the field below so that person who has an account at it will be able to register him(her)self by clicking the Join link on the {1}Sign In{2} page or disable this option.{0}To make the parameters you set take effect click the {1}Save{2} button at the bottom of the section.