Ask HN: Is there a spam filtering web service?

[sam_in_nyc]

After reading Resig's post about Google Groups, I was wondering if there exists a web service that specializes in filtering out spam.

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?

[kngspook]

Well, Google's own Postini does spam-filtering.

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...

[kngspook]

Can someone outline for me the pros/cons of a mailing list vs. a forum?

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.)

[RossP]

Akismet does just this for blog posts.

[_pius]

Defensio?

[sam_in_nyc]

Ah, thanks. Any first hand experience using it?