Sending relevant emails to the prospect will help them to understand more about your product and services being offered. In Pardot you can test your email content by doing A/B testing and identifying your winning audience, target audience, and spam filters.
When to send emails to prospects?
As per the general rule, people are most responsive in either early morning or later in the evening. Sending emails during these times will help you to get the more replies and higher open ratio for your email marketing campaigns. However, all heuristics should be tested internally and Pardot enables you to come up with a hypothesis most relevant to you.