To retailers that create e-mails using responsive code and subsequently believe their messages are set to render properly on any and all devices, Bronto Software says: Not so fast.

E-mail services like Google Inc.’s Gmail or Yahoo Inc.’s Yahoo Mail sometimes fail to process responsive code, depending on factors including the device a reader is using and how she accesses her inbox, either via an e-mail app or a browser, Bronto says. The e-mail marketing vendor audited 106 retailers’ web sites and e-mails in August 2013 for the study, “Responsive Design Provides the Perfect Fit.” The retailers were randomly selected and included some Bronto clients. 8% of the e-mails used responsive code.

“One of the beauties of responsive design is that an e-mail will attempt to scale based on the area that is provided,” says Jim Davidson, Bronto’s manager of marketing research. “The downside is that it is nearly impossible to account for every combination of device, browser, app and operating system.”

Android smartphones had the most trouble during the audit. E-mails created with responsive code failed to display properly most of the time on those devices when opened in the Gmail mobile browser and in the Yahoo Mail app. On the Yahoo mobile browser, the messages didn’t display as formatted by the responsive code. Instead, they opened with the full display as on a desktop, just scaled down in size, Bronto says. With responsive design, e-mails and web sites often load fewer elements on a smartphone screen than on a larger screen, for example, sometimes eliminating certain images, text and other content.

The iPhone, meanwhile, picked up responsive code and displayed e-mails correctly on both the mobile sites and apps of Gmail, Yahoo Mail, Microsoft Corp.’s Outlook mail and the Apple OS mail app, according to the study. The iPad, however, only rendered the responsive display for e-mails via Yahoo’s browser and app. For the other applicable e-mail services (Microsoft does not have an Outlook mail app for the iPad), all e-mails displayed in the full desktop version, the study says.

Other factors that affect whether responsively designed e-mails render successfully include screen resolutions, the way the e-mail is coded, the version of the operating system and the edition of the browser or app on a consumer’s device, Bronto says. Moreover, those factors change often, as service providers continually update their software, with many consumers receiving automatic updates over the web or mobile networks.

There isn’t a quick fix, but the first step is to identify problems, Davidson says. “Marketers should thoroughly test the most common scenarios to ensure the content renders properly,” he says. “A well coded, responsively designed e-mail should be able to cover the majority of use cases. If it’s not, then you should reach out to your design team to find ways to optimize the design and coding.”