In principle, it is possible to use a gradual colour in the background of an e-mail. There are different possibilities.

1. Background image: For a vertical or horizontal colour gradation, you can use a background image, which is repeating on the x or y axis. Background images are not displayed since Outlook 2007 and in a few other freemail providers.

2. CSS: You can also set up a colour gradation via CSS. The CSS properties are also not supported from all clients.