If you are sending Mailers to thousands of customers, how do you know open rate from Google Analytics. If we say URL Parameter Tracking (UTM), we can only track the email recipent behavior only if help click any link in the body of the email content. If the response open rate the mailer and does not click any link in the mailer than, we cannot track the open rate. Then, How the to track the mailer (Email Rate) through Google Analytics. Moreover, it is not possible to place the Javascipt in the mailer content. The Mail client like Gmail, Yahoo, bing will stripover the javascript. So, what is the solution to track the Email oen rate

The Solution is through Pixel Tracking. 

For more information on How to Implement Pixel Tracking, 
http://www.ehow.com/how_5277834_use-pixel-tracking.html

Pixel Tracking URL Parameter details for Google Analytics
https://developers.google.com/analytics/resources/concepts/gaConceptsTrackingOverview#gifRequestClassification