The before image at the top shows the standard approach for an image-only email sliced into different parts, but including using Alt attributes on the images to describe the offers and give reasons to click (best practice).

The after image following refinement and testing shows how implementing a tinted background with text can have a major impact. The new font sizes were:

• Red-brown color box that measured 441 pixels by 400 pixels
• “Limited Time Offer” (font size -- 49 pixels)
• “Free Shipping” (57 pixels)
• “Ends 10-31-07” (35 pixels)
• “Start Now” button (18 pixels)
• “Free Shipping available on orders over $99 to a single destination within the U.S.” (15 pixels)

According to Marketing Sherpa report the uplift in campaign results from switching to prominent text on a background colour was:

• Deliverability 10.1% higher [a lot of spam used to be all image based so this can result in blocking - although care still has to be taken with large fonts which can also be a SPAM signal].
• Open rate rose 28.6% [the text encourages opens to increase - i have seen other tests that show that large font sizes perform best]
• Clickthrough rate jumped 83.4% [this is also helped by including all the department categories as text links at the base of the email - a smart move that all newsletters should also consider]
• Revenue skyrocketed 379.3% [Average order value also increased - perhaps due to showing range of departments]

[My commentary]