To control the animals known as email and voicemail, I recommend reading and listening to them just twice a day so that you can gain control of your time.
Unless your job entails giving people immediate responses to questions, you should be checking in only twice per day. Do not build the expectation with customers and clients that you are always available, thus setting yourself up to be interrupted in the middle of every conversation and every thinking moment. See my post here about saying no, in case you missed it and would like special permission to do it.
Case in point - have you ever been really on a roll, completely creative and getting things done, only to be interrupted by something completely unnecessary and unimportant? (Of course you have, I can see you nodding!) How long did it take you to get back to your great place? Or are you still trying to get there?
The vast majority of the people I’ve observed could easily tell others, “I check my e-mail and voicemail twice a day, at 8 AM and 2 PM. If you need a response from me, then just know that I will check in at those times and respond to your need when I see it.” In that way, the other person knows he has to take responsibility for getting info to you in a timely manner.
You may not feel this particular suggestion would work for you - consider, then, how you could customize this strategy to work best for you.
It feels great to take control and be in charge. Give it a try. Let me know how its going for you ...