Gmail team is quite innovative, in how they introduce features to gmail every now and then. Its impossible to take notice of all these features, and its more hard to put them all in use. Google recently published a gmail guide which can be accessed either online or can be downloaded as pdf.
This is what google thinks about Gmail ninja.
The Gmail Ninja guide is divided in to 4 categories based on the amount they used their gmail.
- White Belt
- Green Belt
- Black Belt
- Gmail Master