Before starting to push pixels, nest tables, and style elements, it's absolutely imperative that we look at the analytics and have a bird's eye view of the landscape we're going to create e-mails for.
Doing this will allow us to understand:
When are our e-mails being opened.
Which days have more opens.
Which hours have more opens.
Whether the season is causing more/less openings.
Which devices are being used to open our e-mails.
What e-mail clients are being most used/less used.
If, for example, the analytics have data stating that Outlook 2013 is rarely used (wouldn't that be awesome), then we may not need to worry about this e-mail client at all.
If the Yahoo Mail app in Android is the most commonly used application and platform, then we can safely use more advanced CSS properties and progressively enhance, knowing that our ideas will display correctly.
Doing market share research is important, but your own analytics are ultimately the ones that will dictate how you...