Choose the communication media based on the nature of the Message, not the personal preference.
Email works great when you want to share a lot of details (especially if you’re sharing it with a large group of people), or when the question you have is extremely simple. If somebody asked you to send her the links to the documentation, or if you have a non-urgent yes/no question, you would use Email.
The great thing about email is that the recipient does not have to be available at the time a message is sent. The bad thing is that you need to be very careful about the words you use because the message can get easily misinterpreted.
You would want to use a direct IM when the question or request you have is simple and relatively urgent. Keep in mind that every time you send a direct IM, you are distracting the other person. He needs to stop whatever he’s doing, shift contexts and then respond to you. After the conversation, he needs to go back to his work, and this change in focus takes time, and affects productivity.
If you have a job that requires you to be reactive, such as customer support, then this is OK. Otherwise, you may want to disable the notifications and check your IMs only during breaks (if you use the Pomodoro technique, which I highly recommend, this would be every 25 minutes).
When you want to explain a complex situation, and need the other person’s constant feedback, you would probably want to use a phone or communicate in person. Sometimes you are not sure what the other person knows, and what needs to be explained. Or perhaps you want to be absolutely certain that the other person completely understood you.
If you want to see how the other person feels about something, the most effective way is talking face to face. That way you can pay attention to the non-verbal cues, such as gestures, facial expressions and voice inflections. This does not necessarily mean that the other person needs to be physically present - video chat can also work very well.
So, next time you start writing or responding to an email or IM, reaching for the phone or scheduling a meeting, spend a few moments thinking whether your approach is really the best way to communicate your message. This awareness will result in better understanding, less conflicts, and it will save everybody’s time.