Metric Search lets you identify People based on reporting related data such as opens, clicks and survey results helping to make your search results more contextualised. To search for employees who are not interacting with your emails, you can create a search for employees who have not opened any emails in a particular date range (for instance, your last five emails).
Search for Non-Engaged People:
Run a Metric Search.
Change the first drop-down from Field to Metric.
The search form will update to allow you to select available System Metrics. For this example, choose Opened Number of Emails in Date range.
The search form will update to allow you to set the number of emails and the date range you want to search across.
Note: The search example above will return all People who have opened 0 emails over the last 6 emails.