Outlook by default comes with a white background, but you can change to a different background with the steps below:
Step 1: Click "New Email" from the Ribbon;
Step 2: In the new email window, click "Options" tab;
Step 3: Move the mouse to the message body window. Click "Page Color" in the "Options" tab;
Step 4: Select a color from the list if you only want the message background in a solid color (e.g., light green);
Step 5: If you want to import an image for the background, please click "Fill Effects" from the bottom of "Page Color";
Step 6: In the "Fill Effects" window, click the "Picture" tab, and select "Picture…"
Step 7: Browse to the folder with images, and click "Insert" back to "Fill Effects" window;
Step 8: Click "OK";
Step 9: The background is now filled with the image;
