The Workflow Administration Console allows you to send an email notifying the request reviewer that they need to review a permission request. Each notification includes a message containing all the information a user needs, to make a decision. You can embed the message in the body, or attach it as a separate document. The reviewer can click the appropriate link on the email, or, they can modify the subject line of the email to approve or deny the request.
Email-based approvals also supports digital signatures to ensure authentication of the message content.