ISPs blocking SMTP connections from dynamic IP address space

Bill Campbell freebsd at
Wed Aug 6 09:49:19 PDT 2003

(quoted text below reformatted to cure severe long/short-itis).

On Wed, Aug 06, 2003 at 11:19:57AM -0500, Doug Poland wrote:

>This isn't so much a FreeBSD topic but a comment and a request for
>resources.  As a long time FreeBSD admin/user I know this is a large,
>diverse, and eloquent community of technical users.  I hope someone can
>point me to a resource or group of users that address this policy.

>Within the last two months both AOL and Time Warner Road Runner have
>implemented port 25 blocks from hosts with IP addresses in the "dynamic
>address space".  Time Warner claims other major ISPs are/will be
>implementing the same policy.

This ``dynamic address space'' is generally devoted to dialup connections,
and DHCP assigned IPs for broadband customers, most of whom are restricted
by their contracts from running any servers.  Their customers are supposed
to send all outgoing mail out through their provider's mail servers.

>Is anyone else uneasy with this trend?  Maybe it's just me and I don't like
>being discriminated against because I don't have the money to own static IP
>addresses.  One would think groups of responsible and technically competent
>users would be organizing against this trend and attempting to make their
>voice heard.

For every *bsd/Linux/Unix user who has enough clue to run servers properly,
there are thousands of clueless folks who connect their Microsoft Windows
viruses directly to the Internet where they're subject to abuse from the
outside world.  It wouldn't be so bad if all the abusers could do is steal
data or corrupt the end-user's machines, and couldn't use them as launch
points for further abuse.  When the ``Code Red'' and ``Nimda'' worms were
at their height, most of the traffic in our Apache logs originated came the
major U.S. cable provider's networks.  This prompted several of the cable
providers to start blocking port 80 to their customer's systems which cut
this source of traffic down significantly.

Our solution for our customers who're running on dynamic broadband
connections is to set up their mail to use uucp over TCP with domains that
MX through our servers here.  I've never had any problems with cable or DSL
providers blocking the uucp ports.  A secondary benefit is that the
customer's e-mail addresses haven't changed in the @HOME->ATTBI->COMCAST
transitions over the last year or so.

INTERNET:   bill at Celestial.COM  Bill Campbell; Celestial Software LLC
UUCP:               camco!bill  PO Box 820; 6641 E. Mercer Way
FAX:            (206) 232-9186  Mercer Island, WA 98040-0820; (206) 236-1676

``When dealing with any spammer, one must always keep in mind that you
are dealing with someone who makes their living through forgery, fraud,
theft, subterfuge and obfuscation.  Stated simply, spammers lie.''
     David Ritz <dritz at>

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