If you deleted all the emails you sent to everyone since the first of the year would not a copy still exist on the machine and mail servers of those that received them.?
There are still copies of these emails as surely as once a pic or mp3 hits the Internet it has a "forever" life in the DIGITAL world because there will always be a copy residing somewhere.
You don’t even need a hard drive to check you exchange mail. Do it from my phone all the time. OWA totally destroys this lie.