My mail.app is not working well.
I read a lot messages forum an dlot of solutions for mail.app is delete
"com.apple.mail.plist" but I can't find it in library/preferences, can you help me please.
There has been a change to Mail in Mountain Lion, partly because of sandboxing changes in the OS. You don't really need to know what that means, but what you do need to know is that the new location for the Mail preferences file is here:
You can copy that path, then choose Go To Folder from the Finder's Go menu and paste it in there to go right to that folder.
All human are not equal. Same for machines and servers.
Get real : iCloud has a problem.
On all machines, permissions are repaired once a week and Onyxed twice a month.