we have a contact missing in our list that is not beiung sync'd from CRM due to "invalid email address"

i have tried to manually add him to my contacts in campaigns as well and get the same error

his email is valid - i tested by sending an email to him from within crm (where his contact and email should sync from )

the only reason I can see that he shows as not valid is that he is an employee of our company so he has the same email domian ending as the zoho account, but I have 10 other employees that are setup as contacts and work no problem

please advise how we fix this as I need this person to receive my email campaigns when I send them