What Can You Do with Email?
https://gsuite.google.com/learning-center/products/gmail/get-started/#!/section-1
Gmail Cheat Sheet:
https://gsuite.google.com/learning-center/products/gmail/cheat-sheet/#!/
Starting Over with Gmail:
https://www.makeuseof.com/tag/beyond-the-inbox-the-power-user-guide-to-gmail/