Below are some Email Marketing best practice guidelines I have based on reading the Eyetracking reports listed below. The example I have shown top right is a great example of an Email Newsletter since it fits the research and the guidelines below.

Heading and sub-heading copy is crucial

This Email eyetracking example shows that users scan the headings and then, if relevant, clickthrough - here they don't seem to be reading the body copy. If practical you should make the headings hyperlinks.

Heading and sub-heading copy is crucial

Within the headings, this summary of an Enewsletter study by usability specialist Jakob Nielsen shows that recipients tend to just fixate on the first two words of the headings, so just as for subject lines, it is the first words that are most important.

Readers scan down the left side of an Email

While this is dependent on the design of the email, the left column is most important as this Eyetracking image from the Nielsen report shows. That's why I have said the HP Newsletter - click top right is best practice.

Email intros are skipped?

Nielsen also suggests in his article that email text intros are skipped according to eyetracking studies. However, I still think they can be a good idea to make the e-newsletter personal, and if you insert body copy links in the E-newsletter intro they will get certainly get clicks if they are relevant.

Large fonts work well

I have read a copy of the Email Marketing Benchmarks report which has several examples - you can see one if you click on this linkand you scroll down to download the Exec summary which agains shows the importance of large headings and prominent buttons.