Apple's Time Machine is a simple and reliable way to backup your Mac to a external or network disk drive but how do you recover a file or email you accidentally deleted?

To use Time Machine restore an individual file or email on you Mac

1. Open a window and browse to the location where the file you want to restore was located
2.  This could be a Finder window like your Documents folder, your Inbox in Mail or another application that backs up with Time Machine.
3. Choose Enter Time Machine from the  icon in the top right of the screen or click the Time Machine app in the Dock. 
4. Find the items you want to restore:
   • Use the timeline on the right edge of the screen to see the items in your Time Machine backup as they were at a particular date and time.
   • By clicking the onscreen up and down arrows you can jump to the last time the contents of the window changed.
   • You can also use the search field in a window to find an item, then move through time while focused the found item.
5. Once you have found the time, select it and press Space Bar to preview it to make sure it's the one you want. 
6. Once you are sure click Restore to restore the selected item, or Control-click the item for other options.