Walnut for Thunderbird

Z 5 z 5 gwězdkow pógódnośony

wót trafalgar dnja Now. 8, 2013 · trajny wótkaz

I receive some email with the walnut background and can hardly read what the messages are. Can you tell me how to get them back to a white background please, I tried everything I know but with no avail. Thank you for your time and effort in this matter, please enjoy your day.