user e-mail name is used as notification from website, can't add that e-mail as a user. Help

user e-mail name is used as notification from website, can't add that e-mail as a user. Help

I am trying to add a user and Zoho keeps saying e-mail is already in use.  when i search zoho the name or e-mail does not come up.  this particular e-mail I think is written in the code for a website submission notification.  Is there a way around not deleting that notification.