1. Upgrade. 1.8 is old.2. Do you run AD or LDAP? If you do not have a lot of emails then you could create filters for them.Alternatively you could create filters to reject all tickets that are not from a certain domain.Please help us to help you by reading and following the posting
guidelines located in this thread: Please read before requesting assistance. The more information you give us the better we will be able to assist you. Thank you.