How do I set the email where agent reports are sent?

The agent report email functionality is configured in body executor control (find in GitHub). It defaults to root@$(def.domain) which is configured in bundle common def (find in GitHub).

See also: def.mailto.

How do I disable agent email output?

You can simply remove or comment out the settings.

The Masterfiles Policy Framework will disable agent email when the class cfengine_internal_disable_agent_email available in controls/def.cf to switch on/off agent email.