Gmail doesn’t allow backgrounds (mostly)
If you include any reference to a URL, your entire declaration will be ignored.
background: #000; /*This will be accepted */
background: #000 url(https://www.test.com/test.jpg); /* This entire line will be ignored */
With that said, if you ever want to back up your background image with a colour, be sure to do it within a different inline CSS declaration.
<td style=” background: #000; background: #000 url(https://www.test.com/test.jpg);”>
Another option is to use the “background” attribute within your TDs.
<td background=“http://www.test.com/test.jpg” bgcolor=”#eeeeee”>