Mailing List Archive: exim: users

preventing mailer-daemon collateral spam

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blists at nobaloney

Oct 19, 2009, 12:24 PM

Post #1 of 3 (540 views)
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preventing mailer-daemon collateral spam

I'm trying to prevent the collateral spam that exists when
mailer-daemons tell us that a user/domain we don't host is sending
spam.

I've googled several hours today but obviously I'm missing something
because I can't find an answer.

If any of my assumptions below are incorrect please feel free to correct
me, but hopefully gently.

The problem appears to be that Mailer Daemons send back email to us even
though our server isn't the sender, and the domain isn't on our server.

My understanding is that exim will always accept mail from a Mailer
Daemon, and I believe that what's happening is that mail is accepted by
exim, and then since it's not deliverable on my server, exim attempts
to send it to the valid MX for the domain.

The simple questions are:

What ACL code can I use to refuse mail from a mailer-daemon if the
recipient is not on our server?

and

In which ACL section should I put the code.

Thanks for any help; I'd really like our code to play properly on the
'net.

Jeff
--
Jeff Lasman, Nobaloney Internet Services
P.O. Box 52200, Riverside, CA 92517
Our blists address used on lists is for list email only
voice: +1 951 643-5345, or see:
"http://www.nobaloney.net/contactus.html"

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tlyons at ivenue

Oct 19, 2009, 12:56 PM

Post #2 of 3 (505 views)
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Re: preventing mailer-daemon collateral spam [In reply to]

On Mon, Oct 19, 2009 at 12:24 PM, Jeff Lasman <blists [at] nobaloney> wrote:
>
> The problem appears to be that Mailer Daemons send back email to us even
> though our server isn't the sender, and the domain isn't on our server.
>
> My understanding is that exim will always accept mail from a Mailer
> Daemon, and I believe that what's happening is that mail is accepted by
> exim, and then since it's not deliverable on my server, exim attempts
> to send it to the valid MX for the domain.
>
> What ACL code can I use to refuse mail from a mailer-daemon if the
> recipient is not on our server?
>
> In which ACL section should I put the code.

You probably have in your acl_check_rcpt ACL:
accept senders = :
Which tells Exim to accept email from <>.

Assuming you have something at the top that sets a list of local domains:
domainlist local_domains = ${lookup mysql { SELECT ... } }

Then modify that accept ACL:
accept senders = :
domains = +local_domains

Whether that's all you need kind of depends on what your config looks like.
--
Regards... Todd
The best thing about pair programming is that you have the perfect
audience for your genius. -- Kent Beck

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## Exim details at http://www.exim.org/
## Please use the Wiki with this list - http://wiki.exim.org/

blists at nobaloney

Oct 19, 2009, 2:07 PM

Post #3 of 3 (505 views)
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Re: preventing mailer-daemon collateral spam [In reply to]

On Monday 19 October 2009 12:56 pm, Todd Lyons wrote:

> You probably have in your acl_check_rcpt ACL:
> accept senders = :
> Which tells Exim to accept email from <>.
>
> Assuming you have something at the top that sets a list of local
> domains: domainlist local_domains = ${lookup mysql { SELECT ... } }
>
> Then modify that accept ACL:
> accept senders = :
> domains = +local_domains
>
> Whether that's all you need kind of depends on what your config looks
> like. --

Thanks, Todd. You've hit the problem on the nose. Thanks!

Jeff
--
Jeff Lasman, Nobaloney Internet Services
P.O. Box 52200, Riverside, CA 92517
Our blists address used on lists is for list email only
voice: +1 951 643-5345, or see:
"http://www.nobaloney.net/contactus.html"

--
## List details at http://lists.exim.org/mailman/listinfo/exim-users
## Exim details at http://www.exim.org/
## Please use the Wiki with this list - http://wiki.exim.org/

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