Also, a requirement for BATV to work correctly is that outbound mail from the internal mailserver going to the Internet needs to be relayed through the Ironport appliance to work.
How can I kill messages with empty field: from < >?
This would violate SMTP RFCs since mail systems MUST accept messages with an empty envelope sender. Check the Advanced User Guide, Chapter 2, Ironport Bounce Verification.
If you turn on Bounce Verification (BATV), the appliance will 'tag' outgoing messages so that it will be able to recognize legitimate bounces and discard messages that appear to be bounces but did not originate on your system.
