While I don't like the name of the service object "CreatesContact", I disagree with the statement that the sending of an email should reside within the create_contact! method. The author's intent is to shield any new developers from methods that say one thing and do another, yet he adds email delivery into the create_contact! method without informing the developer what may happen (unless some magic flag is set somewhere).

A simpler, more contrived example, would be to create a new function create_and_send_email! and place the creation logic and email sending logic in there. And now, when the developer uses the service object, she has the ability to choose between just creating the contact, or creating it and sending an email.

    class CreatesContact
      def initialize(contact)
        @contact = contact
      end

      def create_contact!
        @contact.save
      end

      def create_contact_and_send_email!
        create_contact!
        deliver_contact_created_email
      end
    end