Despamming wholesale dialup

Thu Oct 29 01:47:01 UTC 1998

Harold Willison writes:

> We are offering wholesale dialup ports. When a user connects he is authenticated and can do whatever
> it is he/she wants to do on the net. Unfortuantely some have decided that they will relay spam off of other servers.
> To address this i have proposed installing filters that will only allow these folks to connect to
> port 25 of the ISP that has bought the ports. This way they are not able to relay off of anyone elses machine
> that is using port 25 and the buyer of the ports should have the correct measures set up to prevent bulk mail from
> going out.
> Will this be sufficient, providing that the server they are allowed to connect to has set up his mail server to prevent massmailing..?

We do this already.  AT&T Canada has already committed to doing this.
It will not totally stop spam, but it will impact the way it is done
now, and will force the spammers to pound the mail server of their
own ISP to get the bulk mail out, instead of spreading the load over
the net.  That may successfully break many bulk mail programs.

I would suggest doing it.

Keep in mind one point.  Many people who have domains hosted at various
web providers, where they pick up their mail there, too, use dialup
providers like you and/or your resellers for actual connectivity of
their PCs since they don't get that through the web provider that hosts
their domain.  What that means is that many legitimate dialup customers
will be sending their mail _FROM_ a domain name that is NOT one that
the dialup provider or reseller is necessarily configured to recognize.
Often such outgoing mail is blocked as "source forgery" and these people
just use the SMTP server at their web provider.  The above breaks this.
So some kind of alternative needs to be provided.

We do this only for dynamically addressed dialups.  This is done through
RADIUS so I can turn it off individually per account, and do so on a case
by case basis with explanation of need.  This might mean adding a new
field to your customer account database.  I call mine "allow_smtp".

-- 
 --    *-----------------------------*      Phil Howard KA9WGN       *    --
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