Your Opportunities Emailed in Pitchbox refers to the number of opportunities/websites/blogs to whom you’ve outreached.
Your Outbound Emails are the total number of emails you’ve sent, including each attempt to an opportunity. For example, if an opportunity has four contacts and you have three attempts set up, you can send a total of 12 outbound emails for that single opportunity. Outbound Emails refers specifically to Attempts 1, 2, & 3. Any replies that you send to an opportunity (known within Pitchbox as communications) do not count towards your monthly outbound limit.