Because doing good is always in Style:

What a waste of words. A staggering 500 million Yellow and White Pages directories are printed every year, and most are unwanted by the people who receive them. Now that you can get all the addresses and phone numbers you need online, stop this astounding waste of natural resources by opting out of unsolicited delivery service at Yellowpagesgoesgreen.org. You will still be able to call for directories you actually want, but you won’t receive any you haven’t requested.