In the past, I shared some email rules, habits, techniques and etiquette. What I did not mention was discipline, which is what gives rise to habits. Check this excellent entry on Applying Discipline to Email from  Simplicity Is Bliss. It suggests to write down (possibly in OmniFocus) and then follow simple rules  such as “6:00 am – Inbox to Zero” or “10:30 am – Check for Emergency”. It also offers a great advice to keep your email program closed at all times not specified in these rules.