SUMMARY: sendmail Sender-Domain Blacklisting?

From: Jochen Bern (
Date: Wed Aug 21 1996 - 12:17:41 CDT

One Hour, twenty Minutes, seven Seconds from sending the Request to
receiving the Solution. It'll actually take longer to implement it
than to hear about it. This List is amazing! :-)

I vented:

> THAT DOES IT!! I want my sendmail to refuse Mails as soon as "MAIL
> FROM: <user@that.spammy.domain>" comes down the Line!
> Does anyone have some Insight into what Reactions the above Error
> Messages usually trigger in the Sender? Or know a sendmail (?)
> Implementation already having the desired Functionality?

Thanks to:

Claus Assmann <>
Edward Grimm <>
John Benjamins <johnb@Soliton.COM>
Reto Lichtensteiger <>
Fedor Gnuchev <>


1) sendmail 8.8 is supposed to provide that Functionality out of the Box
   once it's available.
2) For other sendmail 8's, adding several Lines to a Ruleset will do
   the Trick. More Information at .
3) Just choose a new Return Code. (I didn't want to because it's unclear
   - to me at least - what the sending Mailer will do about it. RFC1893
   specifies it, but I could easily enumerate a Wealth of Things that
   are in RFCs but not to be found in current Software ...)
4) Have the following Script deal with it. (This would require every
   User to set it up, and not prevent my System being (ab)used as a
   Remailer.) It'll mail back a Nondelivery notice separately. (... as
   long as the offending Site pleases to accept *incoming* SMTP Connects.
   They're just a big Ad Mailer Site AFAIK, so they mightn't.)
5) Watch out, they might want to retaliate. (Then I'ld *finally* have
   a Reason to walk up to our Network Admin and ask him to ban them
   from the *entire* Site by Means of our Internet Gateway Setup.)
6) Use procmail and send back a Dozen Copies. (I *do* use procmail.
   See 4) for why I didn't want to use it for this.)

Thanks again,
                                                                J. Bern

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