An innocent-looking envelope, addressed to the teen-ager in your family, slips into the morning mail. The envelope is opened. A letter and two photos fall out. Half-nude girls beckon from the photos. For a few dollars, the letter promises, you can get more and better photos perhaps showing less clothing and more action. Shock and anger grip you. "Can't something be done to keep such mail away from the American home?" you demand. "Must our teen-agers be exposed to this?" You investigate and find that the Post Office department, led personally and loudly by Postmaster General Arthur Summerfield, has embarked on a campaign to rid the mails of pornography. But there is a hitch. You also discover that in some quarters the post office attempt to clear up the mails has provoked bitterness and anger. Critics like the American Civil Liberties union and book publishers say the post office tramples on freedom of speech and of the press, and, in its zeal, too often mistakes a classic for a French post card. Through the years, they say, the post office, while attacking pornography, has tried to ban a host of literary classics...