Restrict approval workflow email notifications for Terminated employee

Summary:

We became aware that a former employee updated his home address and the HCM workflow sent the communication with PI data, to an active employee’s work email-which was previously assigned to the former employee. 

Currently, mail store automatically will allow a previously used email address to be recycled 90 days post the termination of the prior “owner”. 

How can we restrict sending workflow notifications to a terminated employee?

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