Solution 1 of 3
1. Hit the ALT keyboard button to display the menu at the top
2. Select FILE then PAGE SETUP
3. Change to 100%, check Shrink To Fit Page Width (see below)
4. Click OK
Solution 2 of 3
1. Open the email.
2. Print via the printer icon at the upper right.
3. The email will open in a printable format
Solution 3 of 3
Update the printer's drivers. This will resolve cannot print issues and print preview failures in Firefox and other browsers.
Also consider preforming a browser reset.