Thread: NDR blocking
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Old 02-10-2005
Rob van der Putten
 
Posts: n/a
Default Re: NDR blocking

Hi there


Juergen wrote:

> How do i filter out NDR-Mails (non delivery report) from being
> delivered ?
>
> In our company exim is the mail-relay for the central MS-Exchange Server.
> Unfortunately the MS-Server (5.5) is not able to filter out the NDRs.
> So the MS-Server sends these reports through the exim-relay out to the
> world !! We like to block this ... in 99 percent these reports are answers
> to SPAM-attacks.
> I tried everything on the exims configuration side...but no way !!
> I can't filter on the subject "Undeliverable", cant, filter on sender
> "<>" ......
> Am i a moron ???
> No idea, what i am doing wrong .....
>
> Any help appreciated !!


The first MTA should do all filtering and make all decisions about which
mail to accept [1].
This server should never bounce but reject instead [2].
The second server should accept all mail accepted by the first server.
Any other setup amounts to harassment.

[1] This means that the first server should know or find out wether the
recipient exists.

[2] For this you need Exim + Exiscan-acl patch.
On Debian linux systems this is exim4-daemon-heavy.
This is also available as Woody backports;
deb http://www.backports.org/debian woody exim4
deb http://www.backports.org/debian woody gnutls11
deb http://www.backports.org/debian woody libmail-spf-query-perl
deb http://www.backports.org/debian woody spamassassin
deb http://www.backports.org/debian woody razor


Regards,
Rob
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