Here are the steps to disable email notifications about blog trackbacks.

1) Sign in to PCWorld.com
2) Click "Community" in the red navigation, or go directly to http://forums.pcworld.com
3) Click "Your Stuff" and then "Blogs".
4) Click on your blog, or the blog you wish to turn notifications off for
5) Click "Manage Blog" from the actions menu
6) Click "Options"
7) Scroll down to "Trackbacks" and uncheck the box for Trackbacks notification
8) Press "Save"

This should stop emails about blog trackbacks. In future versions of the software, anti-spam software will be used to weed out spam trackbacks, so they do not have to be completely disabled.