I attended two webinars last week -- eROI's "Acquire an Eye for Email Design" and WhatCounts' "Designing for the New Email Landscape" -- and the issue came up in both. In the eROI webinar, a participant asked if eyetracking technology had determined definitely that one was better than the other. There was not a clear answer.

So, looking to fill the knowledge gap, I decided to see what retailers prefer. I looked at recent emails from the 100 top online retailers tracked via RetailEmail.Blogspot to see whether they used links or buttons more often for their calls-to-action. (I should point out that many retailers weren't absolutely consistent in their preference, but they did tend to clearly favor one over the other.)

What I found is that 60% of top online retailers preferred links in general for their primary calls-to-action, while 40% favored buttons. For their secondary calls-to-actions (those following the primary/main message of the email), retailers had an even stronger bias toward call-to-action links, with 86% using links and 14% using buttons.

While retailers seem to show a pretty clear preference for links, there's evidence that suggests they should give buttons another look.

"Based on the metrics we've gathered from national online retailers over the course of the past three years, we see a consistently significant lift in click-through when a primary call-to-action is treated as a button rather than a link," Lisa Harmon, the creative director at strategic consulting and creative services firm Smith-Harmon, said. When using buttons, bear in mind the following two nuances, said Harmon:

1) Ideally, a button should be implemented as HTML text "floating" over a background graphic. This allows recipients to see the call-to-action when images are disabled.

2) Too many buttons overwhelm and have the effect of canceling each other out. Reserve buttons for primary calls-to-action only. For secondary points of click-through, use links.

More evidence of the power of buttons comes from MarketingSherpa, which just released a new case study about how publisher SmartBrief was able to increase click-throughs 190% by changing a "related stories" link into a gray utility button. And I know of another email marketer (a large technology vendor) that was able to boost click-throughs by 67% by simply changing a link to a button. So this is something that everyone should be A/B testing.

There were a couple of other interesting bits to ponder that came out of my research:

One is that a few retailers -- including Circuit City, L.L. Bean, MLB Shop and Northern Tool -- routinely paired a button and a link to create their calls-to-action. So that's another option to consider.

A second is that a handful of retailers didn't appear to use traditional calls-to-action at all. There were no "shop now" buttons, underlined text or arrows at the end of sentences. In most of these cases, the retailer used a clickable image of the product as the primary call-to-action. Perhaps they've trained their customers that they can click anywhere to click through. Aiding those emails is the fact that they tend to be focused on a single product.

What do you think?
In your experience, do primary calls-to-action perform better as links or buttons? The Email Experience Council would love to get your input. Just visit the EEC homepage and take the one-question survey there. I'll let you know next week which way the community is leaning.

This commentary is insightful. I recommend it to others.