Re: ISP port blocking practice

["John R. Levine" <johnl () iecc com>]

> > It's been extremely effective in blocking spam sent by spambots on
> > large ISPs.  It's not a magic anti-spam bullet.  (If you know one,
> > please let us know.)
> That simply hasn't been my experience. I still get lots of spam from booted hosts in large provider networks, and yes, 
> that includes many that block 25. As near as I can tell, 25 blocking is not affecting spammers at all, just legitimate users.

I know people at large ISPs with actual data.  Port 25 blocking is quite 
effective.

R's,
John