If you want your email to be memorable, possibly even to go viral, AWeber suggests a simple trick: use a cute animal as part of the art. "But you can’t just slap a random picture of a kitty in your design," the post advises. "It looks out of place, and a little desperate. The key is to use images that work with the flow of your email."

As amusing as the lead to the post is, the rest of it gives excellent design advice.

Blocked Images

Unfortunately, much of the good advice will go to waste because, as Mailer Mailer notes in a separate blog, blocked images can be a significant problem for email marketers, affecting open rates.  When images are disabled, it's difficult to sort through the clutter and identify the call to action or the overall message, it said.

"Recipients need to enable images in order to make sense of the email, thereby generating an open that" the sender is able to track. In some cases, a marketer doesn’t need enabled images, Mailer Mailer also notes—and perhaps, given the trend of most consumers to disable images to protect against spam it might be best to focus on such design tactics.

One such example is an email sent by Harvard Business School, which did not include a call to action. Rather, it was more of an educational or informational email. However, because readers don’t necessarily need to enable images to reach the message, "HBR's open rates are probably inaccurate."

Eye tracking Studies

The decision whether–or more likely, how—to use images must also take into account gender differences in how images are viewed. The Journal of Marketing Research last year published a study that looked at whether designing public service ads about breast cancer did well when they were tailored to women. It seems to be an obvious conclusion, however a series of six experiments led researchers to conclude that design in such ads actually made women less likely to remember the ads. (via the Wall Street Journal).

The results suggest that such a gender-linked ad causes women to become defensive and unconsciously ignore or downplay a message that may make them feel threatened, Steven Sweldens, an author of the study and an assistant professor of marketing at the business school INSEAD, told the Wall Street Journal's Health Blog. Nader Tavassoli of the London Business School and Stefano Puntoni of the Rotterdam School of Management, also participated in the research. Better performing ads were those that used neutral colors, had no female images and started with "hey you", the researchers found.