Recently one of our customers encountered an issue with rendering when sending to the "full version" of Microsoft Live Mail. A few of the fields in their email showed up as blank white space! Our testing of similar emails via Pivotal Veracity's eDesign Optimizer showed perfect rendering in all other top ISP email clients, even Hotmail and Microsoft Live Mail "Classic." The Live Mail "full version" is one that appears to have this unique issue.
What's the issue? In the initial code from our client's newsletter (recently redesigned), the designers did not specify a font color within the text boxes that showed as blank white boxes. Live Mail defaulted the text to white (all other email clients played nice and used the standard HTML default of black text).
In Live Mail full-version, the text is there, you just couldn't see it unless you highlighted it (because of the white background). Here's the added bonus: We tested other emails using undefined font colors, and it did not show the same issue. Live Mail did what we'd expect and displayed black text.
What drove the issue for the client at hand seemed to be a "perfect storm" of sorts. The template uses an outside table and inner tables. The outer table defines a font color of white over a green background. So, it appears the interaction of the outer table having font color defined as white and the inner table with no font specified led Live Mail to display the text as white. I'm not positive what the W3C's say about this, but other email clients (even Hotmail) dealt with it differently than Live Mail. This, by the way, isn't the first display issue found in Live Mail (read this post from Campaign Monitor).
At the end of the day, this is a fairly complex issue and one other email marketers should be aware of. The "full version" of Live Mail acts differently in the treatment of text than other email clients in the marketplace. Pre-testing content with a rendering tool like eDesign Optimizer is even more critical these days as the major players are rolling out regular changes to their email software.