Cannot create zoho mail riyas@anprise.com

Before creating mail in zoho, I used godaddy web mail for anprise.com domain. I have got a referral from my friend's organization to riyas@anprise.com. So I accept the invitation from that mail id and configured anprise.com in zoho. But I couldn't create riyas@anprise.com now. It shows already exist. But this mail id not in user list. Please assist me.