This is a great reminder that when working with test data for stuff like email delivery, always use example.com (or a few other similar TLDs) and not stuff like "test.com" or "acme.com" or "dummyuser.com". I see this all the time by devs and they don't understand the risk and why example.com was put into the standards.
There is a huge chance that you hit a mailbox when you make up an email address.