Jo
Have a look at the bottom of this thread:
https://openacs.org/forums/message-view?message_id=112286 - Rafael Calvo posted a link to one of his student's projects that does email and sms, although the implementation is not a 'standard' part of OpenACS.
Also take a look at the notifications tutorial thread:
https://openacs.org/forums/message-view?message_id=108283 - it's very useful.
Hope that helps.
<Raad>
