My new email rules (for productivity sake)

I have been thinking about setting rules around email for a while. Email is just so consuming and thus so distracting, so I want to setup rules so that I control it rather than it controlling me. So, here are the rules that I plan to implement starting today.

1. Inbox Zero - I have been doing a "sometimes inbox zero" approach for a while, meaning sometimes I will do it and sometimes I won't. I want to do inbox zero and commit to getting to inbox zero at the beginning and end of each work day.
2. Check email five times during the day or less. I'm not sure how I will track this (or if I will), but I think this is a good goal. If I try to limit how often I check email, I will get distracted less frequently and will feel more freedom to plow through my task list.
3. If an email involves a task, do it only if it will take two minutes or less. That is a Getting Things Done productivity method that I think applies well here.

That's all I have so far. What rules am I missing?