A method of mitigating malicious messages communicated from a computer, the method comprising: receiving messages communicated from the computer in a first network; monitoring, at a device separate from the computer, traffic levels for at least one type of message of a plurality of message types received from the computer; limiting, by the or another device separate from the computer, communication capabilities of the computer for one or more messaging types having traffic levels above a corresponding threshold such that the computer is able to continue to transmit the messages associated with the one or more messaging types at reduced traffic levels, wherein a first threshold corresponding to a first type of message is different from a second threshold corresponding to a second type of message, the method being characterised by further comprising the steps of: determining that the outbound message from the computer corresponds to the first type of message; responsive to determining that the outbound message from the computer corresponds to the first type of message and that the traffic level of the first type of message is above the first threshold, preventing the outbound message from being transported to an intended destination by diverting the outbound message to a sink-hole device in the first network, wherein the intended destination is located in a second network different than the first network; and responsive to receiving the outbound message at the sink-hole device, transmitting an acknowledgement message to the computer, wherein the acknowledgement message provides a false indication of successful receipt of the outbound message by the intended recipient in the second network. receiving messages communicated from the computer in a first network; monitoring, at a device separate from the computer, traffic levels for at least one type of message of a plurality of message types received from the computer; limiting, by the or another device separate from the computer, communication capabilities of the computer for one or more messaging types having traffic levels above a corresponding threshold such that the computer is able to continue to transmit the messages associated with the one or more messaging types at reduced traffic levels, wherein a first threshold corresponding to a first type of message is different from a second threshold corresponding to a second type of message, the method being characterised by further comprising the steps of: determining that the outbound message from the computer corresponds to the first type of message; responsive to determining that the outbound message from the computer corresponds to the first type of message and that the traffic level of the first type of message is above the first threshold, preventing the outbound message from being transported to an intended destination by diverting the outbound message to a sink-hole device in the first network, wherein the intended destination is located in a second network different than the first network; and responsive to receiving the outbound message at the sink-hole device, transmitting an acknowledgement message to the computer, wherein the acknowledgement message provides a false indication of successful receipt of the outbound message by the intended recipient in the second network. determining that the outbound message from the computer corresponds to the first type of message; responsive to determining that the outbound message from the computer corresponds to the first type of message and that the traffic level of the first type of message is above the first threshold, preventing the outbound message from being transported to an intended destination by diverting the outbound message to a sink-hole device in the first network, wherein the intended destination is located in a second network different than the first network; and responsive to receiving the outbound message at the sink-hole device, transmitting an acknowledgement message to the computer, wherein the acknowledgement message provides a false indication of successful receipt of the outbound message by the intended recipient in the second network.