The agent report email functionality is configured in body executor control
https://github.com/cfengine/masterfiles/blob//controls/cf_execd.cf.
It defaults to root@$(def.domain)
which is configured in bundle common def
https://github.com/cfengine/masterfiles/blob//def.cf.
See Also: [def.mailto
][Masterfiles Policy Framework#mailto].
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.