Email is quick and easy, but it can get in the way of good communication. Imagine if your recipient reads your message in the line at the coffee shop, behind the wheel in the parking lot or standing at a traffic light. They might forget to respond, and your effort is out the window.
Consider also that many emails go into spam, or users create rules that move some senders into a file only to be read once in a while.
For all these reasons, your subject line should be clear (when you introduce a new subject in an email thread, rename the subject line); you should take care not to numerous people without a need to know; and at the end of your email, close the message stating when you hope to have a response, which gives you a good opportunity to follow up with a reminder.