Searching for time-based workflow emails, creates a great snapshot of which emails are queued up to send. Here, we'll go over the simple steps on how to do just that.
Navigate to Setup. In your Quick Find box, search for 'Time-Based Workflow':
You could then search for specific workflow emails that are due to send, OR just select the search button without any criteria to search for all upcoming emails due to send:
Results would exactly what record the email is based on, the object, the workflow name that pushed the email and its scheduled date!