In this article, David Baker provides a simple formula to testing email creative:
1. Draw a wireframes of several templates (they vary by purpose). These are simply boxes designed for the optimal width and length. Rule of thumb is, keep promotional messages and email that is designed for early lifecycle simple and straightforward and minimize the length. Newsletters and community publications can support longer-form wireframes.
2. Assign a description to each box and bullet the things that you can potentially test within those guides. For example, if your top box of 50x 700 is for “Click to add your email address to the address book,” think about what else you could test in this area. (User Name, Promotional Message, site reminder message, or leave it out altogether). If it’s a header image or text block, then think about testing typographic treatments, background colors, blending with imagery and replacing with imagery.
3. Sit down with your designer and walk her through the wireframes and what options she has for each section. Ask her, if she had two things to test in each box, what would she test — and if you tested them and they worked, what would that do to help streamline creative next time?
4. Lastly, show her past results of emails that performed, which links performed best (in a visual format). Most email systems will give you a click map overlay report to show clicks by popularity and color code.
Do remember, you aren’t limited to the email only. The email is designed to get the receiver from the email to the landing page, so test the exchange between the two. You may be surprised at what can be left out and provide better value at the point of conversion.
Source: Email Insider