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 servers that block unauthorized relaying, which would hinder spammers rather than help them.

Mail relaying routes email through intermediate mail servers, often ones with open relay configurations, so the message headers reflect the relay server rather than the spammer's actual sending server. This obscures the true source IP and domain, frustrating forensic tracing and legal accountability. Open relays on third-party servers are commonly exploited to achieve this anonymity.

A blacklist of open relays is a resource that identifies exploitable servers, but it is the list itself - not the hiding technique - so it does not describe what spammers use to conceal the origin.

Reconfiguring a relay to send email back to the sender describes a bounce or backscatter mechanism, not a method for masking the spam origin.