Deliberately circumventing email security controls, automation detection, and abuse prevention systems of email service providers constitutes a violation of 18 U.S.C. § 1030 (the Computer Fraud and Abuse Act). When done as part of a business operation with intent and at scale, this behavior meets the criminal threshold of intentionally accessing protected computer systems without or in excess of authorization and impairing their integrity and availability. Anti-abuse mechanisms are security controls under CFAA. Knowingly subverting them is criminal, not civil.

I don’t know who runs “za-zu.com”, but they may wish to take down their handbook lest they capture the interest of law enforcement agencies who are working with Google and others major email services ongoingly to locate and take down spamming groups.