The release notes for version 5.0.4 contains the following bullet:
Is there any additional information on this new feature? Is it available only in the NE version?Law Enforcement (aka lawful/legal intercept) can be configured. User
messages can be intercepted and sent to another mailbox. Once intercept
is turned on, any time that the user sends a message, receives a message,
or saves a draft, an intercept message is sent to the specified mailbox with
the original message attached. (Bug 17539)
There is nothing else in the release notes about it. I couldn't find anything in the latest Admin Guide on it. I tried looking up bug 17539 in Bugzilla, but it said I didn't have access to this bug. A search on the forums for the terms "law enforcement" and "intercept" didn't turn up any meaningful hits. Finally, I looked around the Admin console but didn't find anywhere that I could configure this setting.