Adding tracking to emails in Rails

tracking_interceptor.md

This gist illustrates how you would add Google Analytics tracking into your Rails mailers. Add the tracking_interceptor.rb into your path and enable it for your mailers with:

register_interceptor TrackingInterceptor

tracking_interceptor.rb

class TrackingInterceptor
  def self.delivering_email(email)
    if email.html_part
      ERB::Util.url_encode
      # Open Tracking
      # @see http://dyn.com/blog/tracking-email-opens-via-google-analytics/
      tracking_img = '<img src="http://www.google-analytics.com/collect?v=1'
      tracking_img << '&tid=' + Rails.application.config.ga_account_id # Analytics tracking ID
      tracking_img << '&cid=' + email.to.first.hash.to_s # Id identifying user, but need to not be personally identifying
      tracking_img << '&t=event'  # Tells Google Analytics this is an Event Hit Type
      tracking_img << '&ec=Email' # The Event Category helps segment various events
      tracking_img << '&ea=Open' # The Event Action helps specify exactly what happened
      tracking_img << '&el=' + ERB::Util.url_encode label # Event Label specifies a unique identification for this event
      tracking_img << '&cs=' + ERB::Util.url_encode campaign_source # Campaign Source allows segmentation of campaign types
      tracking_img << '&cm=email' # Campaign Medium could segment social vs. email, etc.
      tracking_img << '&cn=' +  ERB::Util.url_encode capaign_name # Campaign Name identifies the campaign to you
      tracking_img << '" />'
      email.html_part.body.raw_source.gsub!(/(?=<\/body>)/, tracking_img.html_safe) # Assumes that the email has proper body tags

      # Click Tracking
      # @see http://www.smartinsights.com/email-marketing/email-marketing-analytics/email-campaign-tracking-with-google-analytics/
      tracking_params = "utm_medium=email&utm_campaign=#{ERB::Util.url_encode capaign_name}&utm_source=#{ERB::Util.url_encode campaign_source}"
      email.html_part.body.raw_source.gsub!(/href=".+?(?=")/) do |link|
        if link =~ /\?/
          link + '&' + tracking_params
        else
          link + '?' + tracking_params
        end
      end
    end
  end
end