A common complaint to this cold turkey method, though, is "what happens when someone genuinely needs to reach me for something important?" I've got a solution that will help you deal with fire drills without backsliding into having your mail program open all day long.
The bottom line is that you want to give your contacts a secondary way to get in touch with you. It's that simple; you might put something in your signature that says, "I don't check e-mail frequently. If this is an emergency, call Jenny at 867-5309."
I've recently run across a slightly higher-tech variation of this trick. AwayFind is a Web service that helps an e-mail contact connect with you if they have a high priority issue.
Here's the deal: You insert a message in your autoresponder or signature like this:
Need me ASAP? You can reach me at: http://awayfind.com/davejoh
(This link works, so feel free to click it to see what it's like.)
When the recipient clicks the link, they have to fill out a short Web form with contact information. You can receive the message as a text on your phone, or have it sent to a different e-mail address (which lets you delegate the work to someone else).
AwayFind is free, but there's a professional version -- for $50/year -- which has a few extra (but, in my opinion, largely irrelevant) features.
It's an interesting idea. AwayFind lets people find you without giving away your home phone number or other personal information. On the downside, it requires people to complete a Web form which, even though it's short, is a bit onerous. There's even a captcha test, which I abhor. If you are looking for some new ways to become more efficient with your e-mail though, AwayFind might just be the ticket.