A suggestion for a MS windows solution. I haven't implemented this yet but I do intend to in the near future (I have only done preliminary research so far). One can install Microsoft's IIS SMTP service provided you have W2K (or above). Then you can use the "Managed Sinks" feature that waits for a TriggerServerEvent. I admit it may need a little XS code if there isn't an ActiveX interface and it's not as simple as an /etc/aliases.