The latest round of spam is easy to spot. You receive an egregious headline with a blank body and an HTML attachment.
Spam filters take a little time to catch up. In the meantime, your inbox is flooded with free ways to get a hard-on (apparently it’s expensive these days).
An Outlook rule that filters out email with .htm attachments seems like it would work, but–amazingly–there is no such rule. If you create one to filter on the message body or header, it generally won’t work either. That’s why these are getting through…they embed it in a way that doesn’t show up.
The easiest fix? Make sure your Outlook junk mail filters are up to date and then temporarily jack up your Outlook junk mail filter to high. Unlike Vista, it usually works quite well. If you’re not using a spam filter at all and your mail server doesn’t have one, I suggest SpamFighter or CloudMark. There are freeware options, like Spamato, but their filtering takes work and they are sometimes unstable.