I'm sorry if I post this question in wrong box.
I have a LAN and installed Zimbra Free version in one of my RH5 servers. In Zimbra Admin panel, I configured an internal email domain like @internalmail.com add some users uses this domain (ex: firstname.lastname@example.org, user2@...)
I'm trying to implement a rule that this Zimbra mail server only be used by internal user accounts of @internalmail.com (send/receive between the internal accts only) and the users can not send out email to any public mail like gmail, yahoo, microsoft.com, ..
Anyone help pointing me out this configuration?