Dylan Boyd assembled a collection of the best and worst email campaigns that he received in his inbox, and presented them on his blog for you to review.
He judged these campaigns based on the following criteria:
1. Design - you only have 2-3 seconds to make an impact
2. Calls to Action - are they clear and above the fold?
3. Concise - too much copy confuses the recipient to know what you want them to do
4. Organization of copy, images and navigation.