Anti Spam software will typically look at the content of the email to try and determine if the message is spam (among other things).
I’ve noticed recently that spammers are resorting to putting their torque me off message in a .pdf file, then use a subject line like:
Then they send it dressed up to look like it might be coming from someone you have an affiliation with, i.e., a real persons sounding name. They either forge the return address (easy) or send it out through their zombies using their return address – again, real people.
So far I haven’t seen malicious code distributed this way, but it certainly wastes your time to agonize over opening it (people in business do not always recognize a legitimate contact, they have so many), only to find it’s a useless stock promotion.
While it’s never a good idea to open an email, especially an attachment from someone unknown, I do recognize that people in business have different circumstances than a home user.
The Spam problem isn’t going away anytime soon, so make sure your internet security software is up to date. I recommend Trend Micro; when you buy it the license covers 3 PC’s, kind of nice for homes with multiple computers. If you are interested, there is a link in the left column of this page (PC-Cillin Internet Security).