Contact not receiving email

We have a Contact List of employees who receive certain employee-related newsletters. We most recently updated the Employee Contact List in August. Since then, one employee who is on the list is not receiving one of our employee-related newsletters even though that person is on the contact list we created in August. The person receives other employee-related newsletters. I have checked the person's engagement in Constant Contact and "Was sent ..." doesn't show for this person for the newsletter they're not getting.

I would appreciate any suggestions.