I would imagine I could create a new filter, send training data to a filter, and send data to a filter and have it return the likelihood of it being spam.
Anybody have first hand experience using a web service like this? If so, has it met your expectations?
I could imagine a setup where you have people send mail to an alias on your domain, route it into Postini, and then into Google Groups. The big problem would be getting users _not_ to send directly to Google Groups. And I'm not sure you'd even be able to tell them (direct vs. filtered) apart in Google Groups...
Except for the registering-over-and-over-again issue, it seems like forums would be preferable generally... (Especially given that most will send you emails with new posts if you ask it to.)
I've done the integration work, but haven't put it into production, so I can't speak to how well the actual service works.