[N3WBI3]

Not true: lots of ISPs don't bother to create in-addrs for even private highspeed connections (e.g., cable modems), and you'd be surprised how many medium -> large sites don't have in-addrs for their outbound email relays :)

And they would be denied until they do. There is no way to fix this problem without some pain to somebody out there. What we need to find is the low hanging fruit and reverse lookup is one of them..

[dfrussell]

And they would be denied until they do.

To my knowledge, the only ISP doing this is AOL and -- to be catty -- a lot of places don't get excited if email for AOL is bounced...

That is, this might as easily be considered a feature :)