A system and method are disclosed for providing enhanced computer network security by scanning data, specifically electronic mail messages, sent to the network before the data is received and transmitted by the network's mail server. An e-mail message is received by a computer network configured to receive data and is checked as the data is received and before it is transmitted to a node on the computer network. The method includes determining whether an external source is attempting to establish a mail connection with the computer network configured to include a data scanning device that recognizes one or more data transfer protocols. Once the data is received the data scanning device begins evaluating the data by first determining whether the data is formatted according to one of the recognized protocols. The data scanning device begins scanning the data for acceptable content and format according to a rule set established by one of the recognized protocols. This is done at the same time as the data is received by the data scanning device. It is then determined whether the data should be sent to its destination on the computer network. If necessary, the data is translated before being passed to its destination on the computer network.