I had a colleague who left my organization several years ago. However, when I send email to a specific group of recipients in Zoho mail, app or website, his old email address is suggested in the "add?" list. This prevents me from clicking "add all" for the group.

Does anyone know how to clean up this list? 

The email account was in our Zoho Mail organization. The user account was deleted. The email address is not in any contacts list.