I have used gmail ON THE WEB since 2005, bought extra storage from google, and have several gigs used there. I have never used Mail on my mac but lately it's been popping up and sending messages to me. I see no reason why I should have duplicates of all this mail on my mac, yet when I used Grand Perspective just now, it shows that about a quarter of my storage is taken up with the mail in the hidden library folder in my user account. I assume I can get rid of it, but would there be problems? This apparently started with Mountain Lion and/or icloud (I have an ipad and iphone). Would there be problems? I tried to delete the Mail app, but without success, I'm told it is needed for Mountain Lion. What IS safe to delete?