(1)Send less. Every e-mail you send will eventually generate pieces of e-mail for you; it's a sort of e-mail karma. The fewer you can send, the fewer you will ultimately receive. Email is easy but it has consequences.
(2)Cc less. They really don't need a copy. Have one off conversations with the necessary stake-holders explaining why you won't be cc ing your boss, the team, everyone in future, necessarily. Only when it matters.
(3)Get real; sort the politics. If the amount of mail you send, if to whom it is CCd are really the sole measure of your success...
(4)Batch more. It is time effective to do (within reason) the same task for some time. Decide when you will check you mail. Check it, action it, send it. Then forget it for a while and get on with some real work.
(5)Handle once only. When you do review your mail, consider it once and once only. Then delete it, file it or note it on your action list. Or possibly action it there and then. With complex and/or emotionally laden mails, don't send immediately but let them incubate and then send during your next batch period.
(6)10/10 quality e-mail not 3/10 out of mind for moment e-mail. There are broadly two kinds of mail. The 3/10 for effort ones which get it out of mind but do not anticipate questions, make it clear what actions are required and are confusingly written. Of course they do only take 90 seconds to write but they'll take many hours of your time sorting out consequences down the line. Then there is the 10/10 for effort mail: explicit, action focused and anticipating the questions the recipient might have. Takes 15 minutes to put together of course. But it saves hours if not days of confusion and poorly executed projects down the line.
(7)Zone: go for density of e-mail rather than continuous pouring of mail. Create a working period when you will do e-mail. Work at it, hard. Then ignore it: enjoy your evenings, enjoy your meals, enjoy your family.
(8)Switch off e-mail in meetings. The brain works best one thing at a time.
(9)Create a filing system. File mails you need to keep. Keep your main in box as near to empty as possible.
(10)Agree ways of working. With Tokyo, with Washington. In a 24/7 working environment you'll fall apart if you try and keep up with the shop being open. Liaise with colleagues around the globe as to what they can expect from you as a response rate. Saying yes to working all hours is saying a potential no to your health,your relationships and your greatest business asset: your creativity.
(11)Pick up the phone more. Phones, even voice mail carry nuances. A mail (even one riddled with little smilies) simply cannot do that.
(12)Remember.E-mail is not free: it has a profound loss of productivity cost if not well managed.