HP Email Firewall Appliance manual Malformed Email

44CHAPTER 3: CONFIGURING MAIL SECURITY

Malformed Email	Many viruses try to elude virus scanners by concealing themselves in
	malformed messages. The scanning engines cannot detect the
	attachment and pass the complete message through to an internal
	server.
	Some mail clients try to rebuild malformed messages and may rebuild or
	activate a virus-infected attachment. Other types of malformed messages
	are designed to attack mail servers directly. These types of messages are
	often used in denial-of-service (DoS) attacks.
	The 3Com Email Firewall analyzes each message with very extensive
	integrity checks. Malformed messages are quarantined if they cannot be
	processed.
	Select Mail Delivery -> Malformed Email from the menu to configure
	malformed email checks.

■Enable malformed scanning — Select this option to enable scanning for malformed emails.

■Enable NULL Character Detect — Select this option to enable null character detection. Any messages with null characters in them (a byte value of 0) will be considered a malformed message.