"The data you have entered already exists" when trying to create deleted accounts in Zoho Mail

"The data you have entered already exists" when trying to create deleted accounts in Zoho Mail

Hi,

Our domain is symsoluciones.com. Working as admin in the control panel:
When I try to add the email account " cesarmedina@symsoluciones.com" and " felixsolis@symsoluciones.com" I get the error: "The data you have entered already exists"

The accounts in mention, were created and eliminated, but I do not know continue to appear as existing.

Any ideas? Can anybody help us?

thanks!