instance method envelope_recipients

# File actionmailbox/app/controllers/action_mailbox/ingresses/sendgrid/inbound_emails_controller.rb, line 79
      def envelope_recipients
        envelope = JSON.parse(params.require(:envelope))
        raise MalformedEnvelopeError unless envelope.is_a?(Hash)
        raise MalformedEnvelopeError unless envelope.key?("to")

        envelope["to"].tap do |recipients|
          raise MalformedEnvelopeError unless recipients.is_a?(Array) && recipients.all?(String)
        end
      end