As more consumers view their e-mail messages on smartphones, ensuring these messages display correctly becomes more important. That’s the feedback from retailers that e-mail marketer Bronto Software Inc. considered when it recently added responsive design e-mail templates to its suite of products.

In March, according to Bronto’s data from its clients, 39% of e-mails were opened on mobile devices. That’s up from 30% in March 2012 and 19% in March 2011. “We have watched while the open rates on mobile devices have climbed quickly,” says Damian Trzebunia, product marketing manager.

Recent research by Google Inc. shows that smartphone owners check their e-mails six times a day on average, and 61% use their smartphones to make purchases.

The built-in responsive code dynamically adapts the e-mail layout and style when it detects a smartphone or tablet. For example, two columns of text and images in an e-mail opened on a desktop computer screen can be automatically rearranged as a single column to be easier to read on a phone, Trzebunia says. Also, the fonts and call-to-action buttons within the e-mail will enlarge to make them easier to tap. “Retailers can design one e-mail and have it display well on any device,” he says.

Most e-mail messages not using responsive design techniques have to be designed for the device they are to be displayed on, meaning a retailer would have to have an iPhone version, multiple versions for Android smartphones, and other variants for tablets and desktop computers, Trzebunia says.

Bronto offers e-mail templates for order confirmation and shopping cart abandonment in the responsive design format. These two templates include locations for retailers to insert order and product information. They also have sections for adding cross-sell and up-sell offers.

Bronto offers more than 130 e-mail message templates, Trzebunia says.