Before I created this blog I came across an interesting tip to syndicate enewsletters via RSS. Through my own research I found that there are less barriers for enewsletters to be successfully sent out via RSS than traditional email methods.
In my research there was some correlation of people who receive RSS feeds and people who read blogs. Since there are not alot of ways to track RSS statistics (as of yet), the profile of a blogger can give you an idea of who may be reading your RSS feed.
There was a resent study, by blogads.com, that had a profile of blog readers. The study estimated that 69.3% of blog readers are aged 29-50, and that 40% of this audience are people who have household incomes greater than $90,000.
Forrester Research released a report called "Blogging: Bubble or Big Deal?", and found that most blog readers are more likely to be male, affluent, and broadband-connected.
ClickZ had an article that referenced Pew Internet & American Life Project that estimates that about 11 million (approximately 50 million) of Internet users are regular blog readers.
If you have not thought about syndicating your enewsletter via RSS you should think about doing this as soon as possible!
eINFO - a collection of articles and studies about email marketing