def sendgrid_enable(*options)
      self.default_sg_options = Array.new unless self.default_sg_options
      options.each { |option| self.default_sg_options << option if VALID_OPTIONS.include?(option) }
    end
def sendgrid_enable(*options)
      self.default_sg_options = Array.new unless self.default_sg_options
      options.each { |option| self.default_sg_options << option if VALID_OPTIONS.include?(option) }
    end
Enables a default option for all emails.
 See documentation for details.

 Supported options:
 * :opentrack
 * :clicktrack
 * :ganalytics
 * :gravatar
 * :subscriptiontrack
 * :footer
 * :spamcheck