Adding emails already in use...

Adding emails already in use...

I have 2 email addresses that are currently hosted by hostgator. I would like to close down my hostgator account, but I don't know how to add the emails to zoho. I tried to "add an email" and it tells me the email address already exists...which of course it does. 
So how do I transfer the two emails over to zoho...Help please... :) 
Sally