I've seen something similar to what you're describing when emails are forwarded. When you forward an email it can cause some unexpected changes to the coding of the email, which can cause colors to bleed out of one box, and into the background color. I took a look at your last few emails though, and I do see that a number of them did have different background colors, including shades of green and gray. If you go to the 'design' tab on an email while editing it, you should see the 'outer background color' as an option to change. If that's not working, and you're not forwarding the emails, I would suggest getting a screenshot of the email with the incorrect colors, and sending it to us directly at social_support(at)constantcontact(dot)com so that we can take a closer look at what's going wrong.
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