Spam Control Considered Harmful

Jon Lewis jlewis at
Fri Oct 31 04:47:40 UTC 1997

On Thu, 30 Oct 1997, Paul Peterson wrote:

> Im not sure of your logic about disabling the "invalid"
> filtering from your sendmail. I wouldn't do it for just one of my
> customers and expose the rest of my customers to spammers that
> intentionally try to hide themselves by faking a return address and/or

Heh...and I thought it was a great _new_ idea of mine. :)
I did try to explain to the client why the rule had been instituted,
though I don't think he grasped it, and let him know that I would only
remove it temporarily and that I would notify his correspondant of the
problem and let them know they need to fix their problem.
> a. It is a proper and complete DNS config to have reverse mapping to
> your ip

Some providers make it very difficult to get this setup, and if you're cut
off from most of the net because your provider is lame, that would suck.

> problems as their problems and not ours. Already there are a ton of TCP
> wrapper applications, FTP sites, telnet sites, Netscape U.S. Encryption
> pages for Navigator, etc that will not allow access with improper or
> non-existant reverse DNS entries. Would you consider not doing
> gethostbynames on your entire web server because one of your web clients

For these things, I can just tell people the client networks are broken
and even give them clues to help fix things...but for the in-addr.arap
mail thing, the issue was "it worked last week...why can't we get mail
from them now?".

> As for responsible service providers disconnecting abusers, we have
> disconnected around 10 of them so far. I guess wer'e luck we haven't ran
> into a Spamford Wallace yet huh ?

We terminated someone recently for spamming through an account elsewhere. :)
She had the misfortune of spamming a huge list of invalid email addresses
from another provider using an account setup to forward her mail to her
FDT account.  We got burried in bounces...most from aol.  The provider
forwarding the bounces to us ended up shutting off smtp for a few days.

 Jon Lewis <jlewis at>  |  Unsolicited commercial e-mail will
 Network Administrator       |  be proof-read for $199/message.
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