Email Security has a future to set the type of each trusted mail relay. Because the list 'Trusted ip's' in ESGateway functions as an open relay type this kind of functionallity is very welcome.
On page 45 –Adding a Mail Relay- step 5 –Select a Relay Type- http://www.websense.com/content/support/library/email/v72wes/admin/WES_Admin.pdf
relay types are:
- inbound
- outbound
- outbound and inbound
- open