A couple of ways:
create a batch file to run both OE and FreeSMTP together - this will at least get it to open. Closing I don't know.
NetLauncher is a Win95/98/NT program that sits idle on your system tray. and waits for you to make a Dial-up Networking connection. When it senses a connection or a disconnection event, it will launch or close programs that you've configured. Perfect for launching email clients. Web Servers and most window applications.