Delayed rejection notification - rescind

Summary:

We have set a 1-hour delivery delay on a rejection notification for a specific phase. We moved the candidate to the rejected state, but changed our mind and returned them back to the prior state within 20 minutes.

We have tested the above and candidates are still receiving the rejected notification even though we returned them to the prior state within 20 minutes of moving them to rejected.

Our question is: Is it expected system behaviour that the candidate still receives the rejection notification once the 1 hour is reached? If so, why? Is this stored in a table once a candidate is moved and cannot be reverted?