Hi Mandy,
You will have to activate the workflow for the release strategies.
In the config for the release strategy you perform the activation on the release code and then in the workflow section you make the config for the workflow. Use User and register the user-ID.
You have to make sure that in the user-ID the email address is maintained. This way the system will be able to pick-up the email address from the user-ID.
The following link might be helpful.
Regards,
Peter