There is ample research about emails increasingly being opened on mobile devices. That brings challenges for marketers in ensuring email optimization for the platform, but also opportunity with m-commerce and immediate product purchasing. Some of the latest data holds that email consumption on mobile platforms soared in the heavy shopping period around Thanksgiving (Nov. 20-26). Email marketing company Knotice says its research found that 45 percent of emails sent by retailers were opened on mobile devices. That was a 50 percent jump from the same period in 2011. Knotice, based on Akron, Ohio, analyzed about 2.8 million emails.