On Sun, Nov 19, 2000 at 10:36:50PM -0500, Amitai Schlair wrote:
> on 11/19/00 4:23 PM, Phil Barnett at [EMAIL PROTECTED] wrote:
>
> > Several of my pop before smtp users have found that their providers
> > are blocking outbound traffic destined for port 25.
>
> I'm having the same problem, so far with EarthLink. Have you encountered any
> other ISPs that do this? If there isn't already a list somewhere, please
> send your villains to me, and I'll compile and post the results.
They aren't really villains, per se.
Imagine that you are an ISP. You've grown large enough to want to expand
outside your original area of operations; you aren't rich enough to place
physical dialup POPs all over the country/continent/world. What do you do?
You contract with one of the big players to provide modem service for
your customers. AT&T, UUnet, Genuity all sell dialup service in bulk to
smaller ISPs - who then provide the customer service, the servers, the
tech support and marketing and so on.
In fact, this is reasonably cost-effective for large ISPs too: AOL does
it, NetZero does it. And what do we know about where spam comes from? Spam
comes from sources where there is no trust between the ISP and the customer,
so that the miscreant can create a thousand throw-away accounts and lose
them at will. abuse@whereever takes a beating. Pretty soon, ISPs close
down relaying for anyone who is not a customer. Shortly thereafter, spammers
start sending SMTP directly from dial-up smarthosts.
Now the ISP is off the hook: the spam no longer contains any particular
links to them. (Well, it doesn't have to, anyway.) But the giant dialup
provider has supplied the IP address for the spammer, and pretty soon the
calls start rolling in to abuse@dialup.
To prevent this, the dialup providers now put in a new element to their
contracts with the local ISPs: port 25 will be restricted on each connection
to only talk to the local ISP's mailserver and backup MX.
...and that's where we are in the cycle now. The onus for removing spammers
is back in the hands of the ISPs who sign them up as customers, but as a
result, honest folk get restrictions on what they can do with their mail.
-dsr-
