I quit mail and shut down my macbook. when I logged back in it was still looping. (Don't know if this is what you suggested). I then quit mail and I think I closed all my internet accounts?? I kept closing mail and shutting down my macbook. It still kept looping. I stopped using my macbook for several days. I finally called the 'contact us' below the apple support communities. (Didn't realize it was an option for me.) A tech named Gene called and he saw the looping email when we did the 'share' thing. After trying lots of things, we realized that the mail preferences in my gmail account were not correct. He helped me change them and then were able to delete the looping message. I don't remember messing with the gmail preferences, so we blamed it on 'the little green people. I'm a retired older person so I could have made the changes and not remembered it. Thanks for you help, BDAqua.