When you hit reply in an email client, that email client is what actually chooses what pieces of code are over-written, and which are left alone. There's no consistent methodology, so making the outcome consistent is nearly impossible. If you try sending yourself this test in several different email clients, and respond from all of them, I'm fairly certain that you'll see different changes from all of them, and some may very well have different containers to keep background colors from bleeding over like you're seeing.
When forwarding Constant Contact emails, it completely changes the colors of the eblast. It's supposed to look like the first image, but when forwarded or replied to, it changes it to the second image. How can we stop this from happening?
Thank you for including your screenshots in this post! These images definitely helped us to understand what you are experiencing. With that said, I apologize you are seeing this change in your forwarded emails. This is something we are continuing to troubleshoot as these formatting changes are caused by the email clients itself. At this time we do not have a workaround, or a time estimate of when it will be resolves. I have however submitted this information in your account. I have also added you to our queue to be notified when it is resolved.