code: function SendgridErrorStatus(response) {
    MessagingServiceStatus.call(this, 'sendgrid');
  
    // There was an error when attempting to send message
    this.state.message = response.message;
  
    // See https://sendgrid.com/docs/API_Reference/Web_API_v3/index.html for errors
    // Currently unable to access the HTTP statusCode of the error response, so we must rely on the error messages
    if (this.state.message === 'Maximum credits exceeded') this.state.code = this.StatusCodes.LIMIT_EXCEEDED;
    else if (this.state.message === 'sendgrid error') this.state.code = this.StatusCodes.SERVICE_DOWN;
    else this.state.code = this.StatusCodes.DEFAULT;
  }
docs: /*
  Error Status
  
  @param response     JSON response object from Sendgrid service