How should you design your HTML email campaigns for maximum readability?

If you design web pages, you probably start with the assumption that most users have a screen resolution of 1024×768 pixels. Then you work your way down from there. But what about when you design HTML emails?

Here’s a very nice HTML email design (click to zoom in):

It was designed no wider than 600 pixels. That’s extremely narrow, by most web designers’ standards.

Even so, here’s what that email looks like in the preview pane of Outlook 2003:

That’s on a 1024×768 screen, with the preview pane set to “horizontal” mode.

Here’s what it looks like in Outlook2003 with preview pane set to vertical:

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