The folks at Litmus.com have prepared this interesting infographic about to boost the results from your email campaigns. Who knew that your readers would be more likely to click on your messages if a button included an arrow icon? And that because of image-blocking features on most email programs, make sure that you use what they call a "bulletproof" button by combine HTML and background codes so that the button will be visible when images are enabled.
Source: readwriteweb.com