Wondering how many people received your email? You can check the stats for any email you've sent - just click on Mailbox and then choose the email you want to view.
On the following screen you'll see how many people received, opened, and took action on your email, plus details on how well your email performed across various metrics. Click on the All menu to filter recipients based on these stats and see exactly which people clicked on your email, among other things.
You can also export these results as a CSV or change the name of your campaign via the Actions button at the top of the page.