A detailed overview of POP, IMAP and GMAIL - http://www.macdevcenter.com/lpt/a/6702

The 12 steps to cure e-mail addiction
<ol><li>Admit that e-mail is managing you. Let go of your need to check e-mail every ten minutes.</li><li>Commit to keeping your inbox empty.</li><li>Create files where you can put inbox material that needs to be acted on.</li><li>Make broad headings for your filing system so that you have to spend less time looking for filed material.</li><li>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.</li><li>Set a target date to empty your in box. Don't spend more than an hour at a time doing it.</li><li>Turn off automatic send/receive.</li><li>Establish regular times to review your e-mail.</li><li>Involve others in conquering your addiction.</li><li>Reduce the amount of e-mail you receive.</li><li>Save time by using only one subject per e-mail; delete extra comments from forwarded e-mail, and make the subject line detailed.</li><li>Celebrate taking a new approach to e-mail.</li></ol>
I think 5 and 6 is useful...

http://www.cnn.com/2007/TECH/internet/02/20/email.addiction.steps.reut/index.html

How to control emails? - http://www.russellbeattie.com/notebook/1008869.html

Why Is Email Still So Terrible? Email is an awful online ID that we use for almost everything. - https://getpocket.com/explore/item/the-other-sara-morrisons-are-ruining-my-inbox