Your account is set to subscribe to all threads you comment on with a weekly email notification, this isn't the default setting.
To see all the threads you are subscribed to:
1. Log in with your account and click on "Settings" (found top right) look down the left hand side and click on subscriptions (under "my subscriptions")
2. Select the threads you no longer want to receive notifications for (note there is an option top right under subscriptions to select all). Go to the bottom of the page and click on "selected threads" from there you can update your subscriptions.
Still under settings - go to my settings - general settings - on this page under "default subscription mode" take your pick select how you will be notified of any future threads you post on.
Follow these directions and you can receive the notifications as you want them.