Custom post render actions

[CR]

Is there a way to use post render actions to trigger a script when an item is done rendering.

I want to send a pop up message from a remote render machine to the users machine when a project it done rendering. I don't want to use email.

The script for render and pop up works locally, but since I am using the watch folder on the remote machine I have not found a way to trigger any script when the render is done or while the watch folder is active.

Any other suggestions??