[rt-users] How to get rid of "Ticket creation failed" email?

[Monti gmail]

I have a queue which ticket reporter can reply to but they cannot
create tickets by email.
when trying to create ticket to this queue there are 2 emails sent
back to the user "Ticket creation failed" "No permission to create
tickets in the queue ".
another email is "Extended mailgate error" with body:
"Couldn't create ticket from message with commands, fallback to
standard mailgate.

Error: No permission to create tickets in the queue "

how can I block these emails to be sent back to the creator?
Can I control the email content?