[rodriguezcommaj]

That's a good question. I'm not sure about StampReady, but Campaign Monitor has a few of the best email designers in the biz working there (namely Nicole Merlin and Stig Morten Myre) who strive for really robust templates. Nicole in particular has written about her approach (typically called 'hybrid' or 'spongey' development), which works without media queries. It's basically using fluid tables, max-width, and MSO conditional tables to get things working and is the best approach around these days. You can read more about it here: http://webdesign.tutsplus.com/tutorials/creating-a-future-pr...

I wouldn't be surprised if Campaign Monitor's email templates built in their builder follow the same approach. MailChimp's too, for that matter. The team there use similar techniques.