So a few days ago I was tasked with creating some HTML emails. Strangely enough this is something I had never done before. So I went ahead with the task of creating CSS/div based emails, using current web standards, as I thought this would be more than suitable. Turns out that this was not the case.
My first client of choice was Microsoft Outlook 2007, and I was surprised to see how badly it rendered what I'd written. With a quick bit of research, I found that Outlook 2007 no longer uses the Internet Explorer rendering engine as it had in previous versions, due to its universally hated security problems. Why they would change the rendering engine instead of "fixing what's broke"(sic) I have no idea, and that's a rant for another time.
Continuing the research, I came across this site detailing CSS support in current email and webmail clients, and was _further_ surprised to find that incomplete CSS support is the norm for most all modern Email clients. It is 2008 isn't it? Yeah there's a lot of green there but there's plenty of red as well. And this isn't even taking into account the actual rendering of the emails; it's one thing to 'support' a style element, but it's quite another if that element is rendered incorrectly.
With this, it seems that the most reliable way to do layout for an HTML email is using the classic TABLE tags. That is disappointing, but certainly information worth knowing.
I also found it interesting as to how bad GMail's CSS support is. Yikes. Just take a gander at the table in that link above. I would have expected more from Google. Then again, GMail IS still in beta...