From the CDA decision: ( http://www.vtw.org/speech/decision.html )
Anonymity 121. Anonymity is important to Internet users who seek to access sensitive information, such as users of the Critical Path AIDS Project's Web site, the users, particularly gay youth, of Queer Resources Directory, and users of Stop Prisoner Rape (SPR). Many members of SPR's mailing list have asked to remain anonymous due to the stigma of prisoner rape. Anonymous remailers are mentioned in this secction: Obstacles to Age Verification on the Internet 90. There is no effective way to determine the identity or the age of a user who is accessing material through e-mail, mail exploders, newsgroups or chat rooms. An e-mail address provides no authoritative information about the addressee, who may use an e-mail "alias" or an anonymous remailer. There is also no universal or reliable listing of e- mail addresses and corresponding names or telephone numbers, and any such listing would be or rapidly become incomplete. For these reasons, there is no reliable way in many instances for a sender to know if the e-mail recipient is an adult or a minor. The difficulty of e-mail age verification is compounded for mail exploders such as listservs, which automatically send information to all e-mail addresses on a sender's list. Government expert Dr. Olsen agreed that no current technology could give a speaker assurance that only adults were listed in a particular mail exploder's mailing list.