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North American Network Operators Group

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Re: ** Forged spamming going on

  • From: Robert Tarrall
  • Date: Mon Dec 21 11:09:00 1998 wrote:
-> some luser off of AT&T DIalup is using (my domain) for relaying
-> mail:
-> Received: from (
-> [...]
-> He is sending thousands of emails to AOL users, who is then bouncing them
-> to me.
-> [...]
-> Thinking about this, there is no solution; here are my options:
-> 1) blackhole AT&T, which does nothing, since the mail is bounces coming
-> from AOL.
-> 2) blackhole AOL, which would fix my attack, but would break all
-> legitimate mail from/to AOL.
-> 3) temporarily blackhole, which would prevent me from getting
-> the bounces, but then I can't send/get legit mail.

You forgot:

4) Deny relaying, which sendmail 8.9.1a will do by default (has worked
  great for us so far), and
5) Deny access to (and,,, etc) which is what we're doing here just because we
  get so much spam directly from such dialup accounts these days.

Anyone have a list of legitimate outgoing SMTP servers for the big dialup
companies (UUnet, PSI, Concentric, AT&T, Sprint, etc)?  So far I haven't had
any complaints about blocking stuff like, but I'd like to make sure
that legitimate email can still get through.

			-Robert Tarrall.-
			System/Network Admin
			E Central

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