E-mail is like a cheap phone call, and I for one am glad that such a medium exists. As it happens, with a little knowledge of Internet email software, it is relatively simple to send a mail purporting to be someone else. This law not only stifles informal exchange via e-mail but also opens up a legal loophole which can be exploited to implicate the innocent. I have seen uncountable instances of e-mail communications claiming to be from someone they aren't. Within the current framework of the Internet software protocol, it's impossible to conjecture with certainty that an unsigned electronic document was authored by or originated from a particular person.
Cryptographic signatures are the only way to establish identities on the Internet.
The act was unanimously opposed by the Internet community and eventually ruled unconstitutional in the Supreme Court. The interest in encouraging freedom of expression in a democratic society outweighs any theoretical but unproven benefit of censorship. Unlike, TV or radio, with their limited channels, the Internet is infinitely segmentable. The users have freedom to choose content which is consistent with their family and individual values. The fact is, the Internet routes around legal control mechanisms, and this frightens the government.