This article provides the info on Dual (Email and SMS) as two factor for user authentication.
For version 6.4.0.
- The mentioned option enables a two-factor code to be sent via both Email and SMS.
- As of 6.4.x this option is made available to synced using Remote User Sync Rule.
- The option is available in the list of token-based authentication sync priorities when creating or editing a remote user sync rule.