Abstract: Described are methods and apparatus, including computer program products, for propagation protection within a network. A transparent network appliance monitors data being transmitted from a first portion of the network to a second portion of the network through the network appliance and analyzes the data to determine whether the data represents a threat to the network. The network appliance transmits the data to the second portion of the network if the data does not represent a threat to the network or prevents transmission of the data to the second portion of the network if the data represents a threat to the network.

Abstract: Described are methods and apparatus, including computer program products, for propagation protection within a network. A management station receives event messages from a plurality of transparent network appliances, each of the event messages comprising a threat indication generated in response to a detected threat in data being transmitted through the respective transparent network appliance.

Abstract: Described are methods and apparatus, including computer program products, for propagation protection within a network. A network appliance repeatedly stores received portions of data associated with email in a buffer associated with an email message until an end of message indicator is received for the email message or a predefined number of bytes have been stored in the buffer before the end of message indicator is received. At least a final portion of data associated with the email message is prevented from being transmitted from the network appliance until a threat determination is made.