emails from unregistered contacts create tickets in the system

emails from unregistered contacts create tickets in the system

Hi,

We have Zoho support set up with a support email address that is used to receive and resond to support tickets.

However, if ANYONE emails this address, the system will create a support ticket even if the FROM address is not in the system as a contact.  The ticket is created without any values for the required fields and is not associated with a valid contact or account.

Is there a system setting somewhere to prevent the creation of tickets from email addresses that are not contacts?  Or to prevent the creation of tickets via email at all?

We would prefer that tickets only be created via the customer portal.  If users can create tickets via email then we certainly do not want unregistered contacts to have this ability as anyone (ie non-paying general public) can create support tickets in our system.

Thanks,
Scott