It means that if it sent the email that the ticket wanted, it would send an email to a email that is either collected or used by the system. Which would result in osTicket picking up the email, making/updating a ticket, which would in turn send an email, repeat infinitely.
You would need to identify what email the system wants to send to, and find out why the loop is happening. It could be that the system is using an email that is a mailing list, etc.