UM 2.x Remove grey background from HTML email templates

How can I get rid of the grey background in HTML emails? The grey background is not in the HTML code for the email templates. Where is the grey coming from? Even if I strip out all the html code, the grey background remains if “Use HTML for E-Mails” is ticked.

The default email templates for UM2 have code for a white background div that should overlay the grey background, but in my install it does not render, so the grey background appears between every div. Ugly and hard to read. For now I have removed the white overlay div and am using very simple html without background, so standard black text displays on the grey background. At least it is readable.

My current UM install is 2.0.9. This was a difficult update from 1.3.88 to 2.0.4 then through each subsequent update to 2.09. It took me 7 days and untold hours to slog through each function that broke during the update. All my custom email templates were lost during the update, so I had to re-write and format each email template again. Everything appears to be working again now, except for this last glitch with the email format.

Has anyone else experienced the grey background issue? What is the solution?