Spaming relaying and Port 25 Blocking

Jeremy Porter jerry at
Wed Dec 23 06:09:25 UTC 1998

Sigh, ok  I wasn't clear here.  We are blocking our dialup ports from
accessing Port 25 outbound without going through a device that limits
the numbers of emails that they can send.  This prevents OUR customers
from using other's RELAYS.  (This IS something UUnet could impelement).

It operates as something along the lines of a know your customer,
in that it will 99% stop throw away dialups from using relays.
And it won't break people's wholesale dialup business, like complete
blocking would.  Key thing is RATE limiting.

Fundmentally the same as source address ingress filtering, only

The same request is made that I'm not interested in the legal side
unless you are licensed to pratice law in Texas.  (In which case
you would know better than to give out random legal advice in the first

In message <199812222129.PAA19820 at>, Jeremy Porter writes:
>Has anyone got any operational experience with blocking Port 25 from
>dialup blocks or instituting a "transparent" proxy system that limits
>email volume?  I will summarize and respect privacy requests regarding
>information.  This looks to be fairly straightfoward to do with
>NAT/"L4 switch" (I hate that term), such as a Alteon or Foundry.
>I would like to have something like this in operation by end of Q1 99,
>but want to minimize or eliminate customer pain.  This way anyone
>running proxies on downstream sites, or dialup farms, would have not
>excuse to not prevent dialup accounts from sending to relays.
>Those of you in my .procmailrc need not reply, as I won't see it anyway,
>as we are completely aware of the legal issues involved and know what
>we are doing.

Jeremy Porter, Freeside Communications, Inc.      jerry at
PO BOX 80315 Austin, Tx 78708  | 512-458-9810

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