We don't send out consumer emails through Sandbox because we want to eliminate the possibility of a real consumer receiving a test email. However, we do generate those emails, and you can view them by going to Users → All Users, clicking on the user account you are testing, and then clicking on the "Emails" tab within that user account.
Please note that the exception here is any "X days" notification emails which are not being generated since we do not run any scheduled tasks in Sandbox accounts. Therefore, anything that should run in the future based on date or time will not run, no emails will be sent based on that event.