For everyone downvoting Jamie, there are so many bloggers who have released their data on interstitials. In many cases, the trade-off is worth it: annoy a small percentage of users, but enjoy higher overall conversion rates.

I agree that there could be better ways to serve the popup (time-delay, wait until 2nd article viewed, etc) but if your argument is simply "turn it off because I dont like it, and it will never work" -- go look it up. One such example:

http://danzarrella.com/my-data-shows-email-popups-work-and-d...