If the person is no longer working at the company, email enrichment is not the issue (it is the right email) but the underlying contact data is wrong ie. outdated data
What are you using to get the person's name in the first place? Apollo? Linkedin? Something else?
Also note - depending on the industry you may have higher or lower rate of these depending on turnover and/or how often people in this industry are updating their Linkedin profile etc.