1) Select Your Account link (at the very top of the screen).
It will take you to a page full of setting for your account. Look near the bottom for a block called "Account Preferences". Look for the link to your Email Subscriptions:

2) Select Email Subscriptions.
This opens a page of all kinds of emails you may (or may not) want to receive as part of your service. Look for the Friends Movie Note email:
Make sure it's not selected, and then you won't receive emails you don't want. Trust your Friends to manage this (but feel free to explain it to them if you're worried). I hope this helps. At worst, it's a start. (At best, we can move onto bigger tasks!) Enjoy.