The average time it takes from the initial customer email to the resolution of their query or issue (hours or days). Customers value quick resolutions. Monitoring this KPI ensures that issues aren't being drawn out over prolonged periods, which could decrease customer satisfaction.
Total resolution time for emails / Number of resolved email cases
If it took 40 hours in total to resolve 10 email cases, the average Reply-to-Resolve time is 4 hours.