If I was not such a nice guy i would quote you just to be, well, less than nice and see if i could fill your inbox. Click on your control panel and under general settings you can turn it off.
I don't feel like looking for it, but I had the exact same problem until I looked around and turned that feature off- Think is probably right.
Go to My Control Panel Under the Left Menu, scroll down till you see Settings. Click on it. (it's right under User Tagging) Scroll down the screen until you see 'Quote Emails'. It's the second last option. Disable this.
Go to your setting options under the User Tagging Options block of your control panel (This is further down on that column than the General Settings option). Now put a check mark in all of the various Disable E-mail notifications options. Click save settings -- and Bob's your uncle.