For the past 3 months, I've noticed that when I choose White for a background in my emails, it's now a very light beige, or cream. It's no longer a crisp white. Chatted with a CC rep, showed him screenshots. He agreed that the background looked cream-colored, even though on his end it looks crisp white. Checked with a couple of friends who receive my CC emails, and they said the background was a cream-color as well. Not sure what happened - I've used CC for years, never had this issue before.
I checked without my blue light filtering glasses, and the whites all looked the same to me even in the screencaps you submitted to Chat support. When I checked in your account, all the whites of our UI and in your emails' inner backgrounds were the same hue. As a final confirmation, I used our eye dropper tool to pick up the coloring hexcode, and it was all #FFFFFF for our site, your emails, and even your screencaps that allegedly show the off-whiteness.
My conclusion is that this is simply a trick of the eye based on the other colors of your email around the white inner background, and the fact that the hexcodes even in your screencaps are the same #FFFFFF indicate there is no actual off-whiteness present. Unless the screencaps submitted are also somehow not capturing what you're describing, in which case I'd strongly advise using some kind of eye dropper tool available on your device or the web. Then you can test on your end, and prove once-and-for-all whether or not that your inner backgrounds are indeed white.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ William A Community & Social Media Support