There are ways to send SMS messages that don't require SMTP. TextBelt is an example of a free web services texting API. There are other commercials ones out there as well. If you have a modem that can send SMS texts, Gnokii might be of use. So, for the web services based approach, I figure you would need to modify your Notifier scripts to use curl or wget instead of the normal mail command.
Having said that, I don't have any experience or scripts ready to go with these other methods. Might be something to try out when I find the time or if you have luck, please post since it does come up periodically.