One of our dedicated MVP's, Patrick Schmid, reported in his post here that:
If you provide an RSS feed for your blog, then there is a good chance that you use FeedBurner. FeedBurner is a great tool to get accurate statistics on how many subscribers an RSS feed has for example. Unfortunately, FeedBurner doesn’t count any subscriptions from Outlook 2007 or IE7. It looks like FeedBurner just doesn’t know that Outlook 2007/IE7 can be real RSS readers. This is a pretty annoying problem for me, as I would assume that a large number of you are subscribing to my blog via Outlook 2007.
For Outlook 2007 we will unfortunately not be able to report any custom user agent string for our RSS aggregation. Due to the way we integrate with IE across many parts of the application (the WININET stack is the underlying infrastructure for all of Outlook’s internet communication), we cannot easily and safely change the way we broadcast ourselves when connecting to external servers. To do so would require a fundamental change in the way the WININET stack is called from Outlook and could affect all of the Office applications. The scope of this fix is unfortunately outside of what we can provide this release.
We are going to work with Patrick, IE, and the Feedburner folks to see if there is anything else we can do.
Thanks Patrick for helping us diagnose this.