ISPs blocking SMTP connections from dynamic IP address space

Doug Poland doug at
Wed Aug 6 10:14:13 PDT 2003

On Wed, Aug 06, 2003 at 11:37:21AM -0500, Bruce Pea wrote:
> --On Wednesday, August 06, 2003 12:33 PM -0400 Steve Hovey 
> >
> >I now block ip's with no reverse dns
> We are doing this as well. We get a fair number of complaints from people 
> who's mail doesn't get delivered but we tell them to fix their DNS so we 
> know someone isn't trying to spoof us. So far, 23 out of 25 organizations 
> complaining have fixed their DNS.
This isn't a reverse DNS issue.  This is the connecting host with an
IP address in a range ISP's have decided is "dynamically assigned".
This IP address range is then blocked from connecting on port 25. I
believe the FreeBSD mail servers use reverse DNS to help control spam
and I'm OK with that.  I have resolvable DNSs but am being blocked
because my IP is in Roadrunners 24. network.


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