A couple of my favorite snippets from the 12-steps:
Deal immediately with any e-mail that can be handled in two minutes or less but create a file for mails that will take longer.
Again with the files. And two minutes or less? Practically all of my e-mail can be dealt with in two minutes or less. The problem is that I’m checking it every two minutes or less.
Establish regular times to review your e-mail.
I already have regular times, they’re just a bit more regular than I would be considered sane. … C’mon, c’mon, I’ve e-mail to check
I find I am often much better off if I simply “forget” to open Thunderbird for parts of the day.