Looking for a script that scans subject line at server level..

I set up a sendmail server on a fedora core linux box..

My need is to run a script that will scan incoming e-mail in one e-mail box and send an e-mail to my wireless device if certin words are in the subject line.

I have a Rule set up with my office client, but I think it will be more efficient if I can do it at the server level, but I have no idea how to get started with this???

Any help?

Thanks,

Mike