I have an app that send emails. The body of the email can be defined as HTML. I want to use the bgcolor attribute of <body> to set the background color of the email. Simple enough. http://www.w3schools.com/tags/att_body_bgcolor.asp
However, "The bgcolor attribute of <body> is deprecated in HTML 4.01." and "The <body> bgcolor attribute is not supported in HTML5. Use CSS instead."
So, I'm using Thunderbird as my email client, which is not a browser of course. If I use the bgcolor attribute, Thunderbird recognizes it and all is well.
So, how do HTML / HTML5 / CSS and non-browser apps like Thunderbird work together / or not work together? If I use the bgcolor attribute to set the background color of the email, do I run the risk of it not working at some point in the future? If yes, would that imply that Thunderbird no longer supported HTML 4, but instead switched to HTML5?
Thanks for any feedback.