• by Mark Walsh  @markfwal, May 17, 2011

Mobile still makes up a small proportion of the email audience, but is growing quickly, according to a new study. The proportion of people who access email on mobile phones has nearly doubled in the last six months to 16% from 9%, even as checking email via Webmail services like Yahoo Mail and Windows Live Hotmail fell 10%.

The findings come from a study by email certification and reputation monitoring company Return Path, based on tracking of roughly 140 email opens from more than 90 different business clients from October 2010 to March 2011.

Webmail is the main platform for viewing email, with 48% of the audience. Desktop computers account for 36%, and mobile accounts for 16%. When it comes to desktop access, Microsoft Outlook email program commands nearly two-thirds (63%) of email views.

Not surprisingly, mobile email use tends to spike on the weekend as people keep up with messages away from the office or home. The research showed that mobile email use maintains a steady pattern during the week, with a rise beginning Thursday that reaches a peak on Saturday before tapering off Sunday, while still remaining higher than weekday use.

Conversely, desktop use is higher during the week, peaks on Wednesday, and drops off dramatically on the weekend. Like mobile email, webmail also sees an uptick on the weekend, and hits a low on Wednesday.

"The art of 'designing for the small screen' may be evolving to the art of designing for the reader on the go," stated Bryan Dreller, product manager at Return Path. "While still critical to the email design process, rendering quality itself is still secondary to sending the right message at the right time."

Growing adoption of smartphones and tablets is helping to increase mobile email use. Email reading on the iPad has grown 15% in the last few months. Return Path expects that percentage to continue growing and advises marketers to adapt to expanding email use on tablets.

A Pew Research Center study released last July found that 34% of U.S. adults send or receive email messages, up from 25% in April 2009. Email accounted for just 1% ($195 million) of total online ad spending last year, roughly flat with the prior year, according to the latest data from the Interactive Advertising Bureau.