4. Use time to persuade
If you need to persuade your reader to take action, first justify a deadline with a time-based reason, then state the request with a deadline.
Always consider what will happen if the reader fails to act as you wish. Sometimes, such a consideration will show you a way to offer a nonresponsive affirmative option, such as, "As you know, we need to send out the newsletter on Thursday morning, so if you have any changes to suggest, please send them by the end of the business day on Wednesday." With such an option, you can proceed with your work without having to chase down nonresponders.