Thanks to Heather Fletcher of Target Marketing for these tips, especially #3 about tabled html.
Tabled HTML is always the winning bet. Whoa, it’s so 1999 that Third Eye Blind should be playing in the background. Seriously though, email clients aren’t exactly bastions of innovation. Anchor your creatives in tabled HTML to ensure that they render as you intend. Depending on the client, certain elements of other doctypes may render as planned. But, at the end of the day, <!DOCTYPE HTML PUBLIC “-//W3C//DTD HTML 4.01 Transitional//EN” “http://www.w3.org/TR/html4/loose.dtd”> is the only markup document type that is 100 percent correctly parsed by all email clients.