In many states sending spam is illegal. Thus, the spammers have techniques to try and ensure that no one knows they sent the spam out to thousands of users at a time. Which of the following best descr

A blacklist of companies with restricted relay configurations describes a defensive security posture and would not help spammers send or hide the origin of email.

Mail relaying routes outgoing email through one or more intermediate mail servers - often misconfigured open relays - so that the relay server's address appears in the message headers instead of the spammer's. This technique effectively hides the true origin of spam by inserting a chain of servers between the spammer and the recipient, making attribution difficult.

A blacklist of companies with wide-open relays could be used to locate abuse targets, but the blacklist itself is not the technique spammers use to hide message origin.

Reconfiguring a mail server's relay to return email to the original sender describes a bounce or backscatter scenario, not a method for concealing spam origin.