The domain of the user when using single sign-on (SSO).
This property is only applicable when using single sign-on (UseSSO is set to true) and if the domain of the User (e.g. firstname.lastname@example.org) is different than the domain configured within the SSO service (e.g. email@example.com).
This property may be required when using the ADFS, OneLogin, or OKTA SSO services.