article by Jill Duffy on email management, March 5, 2012.
Also a two minute video on this page that explains the tips:
1. delete (useless stuff) first when you open the inbox
2. Write short
3. Reuse sent messages
4. Reuse subject lines
5. Use groups/distribution lists
6. Sort to delete
7. Turn off notifications
8. Close email to focus
9. Use auto-replies wisely
10. Delete (or at very least, file messages into folders)
11. Take out the trash (daily) or set up auto-dump