SpamCop operates an anti-spam "blocklist" that can be used by third parties as a reference to block junk e-mails. The list is compiled by users informing SpamCop when they receive an unwanted e-mail. SpamCop then uses the information to determine the Internet Protocol (IP) addresses used to send the messages. OptIn is suing SpamCop, arguing that its activities interfere with OptIn's business by causing ISPs to block its e-mail marketing. However, the company is run by Scott Richter, an individual dubbed the world's third-largest spammer by the Register of Known Spam Operations. In December, Richter was named in a lawsuit by New York Attorney General Eliot Spitzer for sending deceptive spam. OptIn also alleges that SpamCop's refusal to disclose the identity of the complainants could add to potential violations of the new US Can-Spam Act which requires the removal of people from mailing lists if they chose. This, it argues, is impossible unless the complainant can be identified. The imposition of the restraining order is no indication as to whether SpamCop's blocklisting will be barred in the long term. The restraining order remains in place until 20th May when the dispute goes to trial.