Prevent ticket creation by email

Dear all,

I have a queue which has some mandatory custom fields. I wish to prevent ticket creation by email for this queue (and not any other queues) but still allow communication between requestor and owner by email once the ticket has been created. Is this possible? The users will be creating tickets in this queue using SelfService. If this cannot be done, but instead the email returned with a message stating what to do (ie login to SelfService) then that is fine too.

We are using RT 3.8.8.