There’s no “definitive” system. The best framework is the one that works for you. Ideally, it should model your work style, supporting the way you work. Bonus points if it’s low-maintenance, fast to set up, and adaptable as your work changes.
Some people like to use folders with specific actions (do, delegate, reply), while others prefer the deadline-driven approach (today, tomorrow, next week).
These are internal notifications, emails from the corporate office or from team members who want to keep us "in the loop."
If you see your name in the "cc" field instead of the "To" field, chances are it's an FYI email. Consider filing it in a "To Read" folder, and tackle it when you have time.
E-mail is not a substitute for conversations.
Avoid asking open-ended questions and save yourself from the “boomerang effect” (that’s when you invite more email into your inbox than you intended, as a result of having sent out an email in the first place). Be concise in your message and specify the TL;DR and/or requested action upfront.