Your API Dashboard is located in your account off the left hand menu. Every-time you make a call to the API, it will record the results, so you can quickly see big picture overview of your usage and your results. No emails are saved, just a count of the results.
In the API Dashboard, as seen above, you will have a drop-down the drill into the details of the invalids, do not mail, and unknown status codes. And be able to graph by daily or monthly trends to get a more in-depth look into your email validations.
In the above image, I clicked on the status I didn't want to show, leaving just the trend of the invalids. To get further details about the invalid, change the menu on top to "Invalids by Sub_Status"
Now you can see the sub_status break down of the "Invalids" emails. It's a very powerful tool, to allow you to see usage summary by day, months, and even years with a visual representation of the health of the emails you are passing through the API.