Identifying the precise sender of a commercial email isn't always easy, but a new set of rules from the FTC aims to shed some light on the situation.

Earlier this week, the FTC voted unanimously to modify the CAN-SPAM Act of 2003, after a three-year public comment period.

The new rules mandate that each email contain an opt-out mechanism for the user. Senders will have 10 days to comply with the opt-out.

But the term "sender" has also come under scrutiny from the FTC because of the proliferation of emails that contain several brands.

Under the new rules, advertisers that join forces for a new email (imagine a cross-promotion between a major fast food chain and a Hollywood blockbuster) have the ability to nominate a single company as the sender of record. That company's name will appear in the sender field of the email, and they will be held responsible for administering the opt-out mechanism.

That's a welcome change to some email marketers.

"Since CAN-SPAM's inception, there has been pervasive confusion in the marketplace over responsibility for including opt-out links in email, which has led to inconsistent execution of the unsubscribe process, increased risk of unsubscribe list abuse, additional and unnecessary costs for advertisers, and an overall reduction in the efficiency of the medium," said Matt Wise, president and CEO of email marketing firm Q Interactive.

More information on the changes to CAN-SPAM can be found here.

Meanwhile, CAN-SPAM also proved that it packs quite a punch. This week, MySpace won $230 million in damages in its suit against two notorious spammers.

MySpace won its federal case against Sanford Wallace and Walter Rines after the pair failed to appear in court on Monday, according to an Associated Press story.

MySpace may have trouble collecting its money, but Hemanshu Nigam, the company's chief security officer, called it a major victory because it could deter others from attempting to spam the site's members.

As for spam itself, the practice recently marked its 30th anniversary and doesn't appear to be going anywhere.