They lie: “You indicated that you want to receive special Ziff Davis offers when you provided your email address to PC Magazine. If you prefer not to receive this type of special offer from PC Magazine, please use the following link:”
This is the first message I have received using that email address since it was created on September 15, 2003 at 1:46:07pm. You think if I had opted in to getting email from PCMagazine, I would have gotten at least one message in the 879 days (almost 2.5 years!) since I gave them an email address. So, I have blocked both pcm-marketing.com and omessage.com from my mail server. And of course, you should never opt-out of stuff you didn’t sign up for.
An interesting idea for a SpamAssassin rule: If a domain name mentioned in the headers of an email mesage does not have content on a web page at the same domain, give it a couple points. So this message would have scored at least four points, as both omessage.com and pcm-marketing.com do not have a web site. I also wonder why omessage.com doesn’t have any information in their whois records?