Not surprisingly, one of the first questions marketers ask is, "What do I need to do to ensure my mobile customers have a positive experience with my email?" Lacking an adequate set of published resources, we powered up our mobile email rendering solution and began examining what a variety of business- to-business and analyst newsletters were doing to optimize the mobile user's experience. Our hope, of course, was that as purveyors of industry expertise, they were likely to have implemented all the latest best practices and would serve as guiding lights on how to do it right.

What we learned is that we all have a lot to learn. Even though the newsletters we examined were not universal guides to how to do it right, what they did do wrong can serve as lessons for us all.

Keep it light -- 20kb or less. Forrester Research sent a lengthy newsletter which, while not image-rich, was still heavy on text. The W3C recommends page sizes of 20kb or less for mobile devices - Forrester Research's email, however, was 204 kb without images and 213 with images downloaded - 10 times larger than recommended. The result, slow download times, higher data charges for recipients, and in some Mobile Email Readers, an incomplete email, as size thresholds were exceeded.

Use multiparts -- and don't forget the text part. Adweek sent an HTML-only message. Not unusual, unfortunately, as many mailers now either send HTML-only, or send a multipart but fail to populate the text part. The result is unintelligible for recipients using the latest BlackBerry phones. Unlike the iPhone or WM6/Mobile Outlook platforms that render the HTML part, BlackBerry will render the text part of a multipart message. If an HTML-only email is received, it renders the raw HTML code -- an ugly experience at best.

One column is better than two or more. Fierce Wireless used tables to create a popular two- column layout. Unfortunately, even though users of Palm mobile devices do get a variation of HTML, the installed Palm Garnett reader does not support tables. Instead of presenting the two columns next to each other, the newsletter renders as one long column with the right column following immediately after the left column.

Don't rely on images to convey critical information. Business Week sent a terrific discounted subscription offer conveyed primarily via a series of images at the top of its email. Those marketers who care about and optimize the message for desktop and Web-based email readers already know this lesson: Don't rely on images to convey your brand or critical calls-to-action, because many email readers (AOL, Hotmail/WLM, Outlook 2007) now have images disabled by default. This rule is pretty universal, as it applies to the most popular Mobile Email readers - images either can't be enabled or are disabled by default. If you do use them, at least incorporate descriptive ALT-TAGS so readers realize what they are missing.

The takeaway here is that mobile is on the move. People are walking, driving and flying with their email in their pocket. As the mobile market grows and becomes a staple rather than an incidental, understanding the limitations of the platform will be crucial to establishing and maintaining a clear and compelling communication channel with an "on-the-go" audience.