How about sending her messages fit for the hour: not in black and white but maybe gray and black?
In Mac OS X Mail, changing an email's background color is easy — but you have to know where to look.
Change a Message's Text Background Color in Mac OS X Mail
To set the background color of a message you are composing in Mac OS X Mail:
- Select Format | Show Fonts from the menu (or press Command-T).
- Click the Document Color button (it shows a document icon).
- Choose the desired color from the desired color picker.
Note that you can only change the entire message's background color and not, say, highlight selected text with a different color.