externalId

The external ID provides additional security for your IAM role. You can use an ExternalId with the IAM role that you use with Amazon SNS to send SMS messages for your user pool. If you provide an ExternalId , your Amazon Cognito user pool includes it in the request to assume your IAM role. You can configure the role trust policy to require that Amazon Cognito, and any principal, provide the ExternalID . If you use the Amazon Cognito Management Console to create a role for SMS multi-factor authentication (MFA), Amazon Cognito creates a role with the required permissions and a trust policy that demonstrates use of the ExternalId . For more information about the ExternalId of a role, see How to use an external ID when granting access to your AWS resources to a third party .