That is an option on every comment/reply page on the site - unticked by default for logged in users, but ticked for anonymous posters.
If you do NOT want a notification by email on articles/forums/blogs/polls that you are posting in, please make sure that is unticked.
For logged in members, if you DO want that notification, you can click edit on the "my account" page and make the relevant selections.
Another note - I get an email everytime the website fails to send an email, so if you are going to enter a fake email, please please untick that box. Saves me having togo through a long and boring list of emails informing me that an email to X was undelivered which was sent due to a new reply to topic Y.