Relaying messages through a firewall

The present invention extends to methods, systems, and computer program products for relaying messages through firewalls. A message relay negotiates first communication parameters with relay components inside a firewall and (potentially different) second communication parameters with applications outside the firewall. The message relay receives a message from an outside application in accordance with the second negotiated parameters and maps an electronic address in the received message to an inside application. The message relay transforms the message and sends the transformed message over an established connection through the firewall to a relay component in accordance with the first negotiated parameters. The relay component receives the transformed message and transforms the transformed message back into the message. The relay component delivers the message to the inside application in accordance with the second negotiated parameters.