[Mimedefang] Validate forged local sender
sgcarr at civeng.adelaide.edu.au
Thu Nov 27 08:13:13 EST 2008
Thanks - done some testing and will implement over the weekend.
I added /etc/mail/forward
Joseph Brennan wrote:
> On Wed, Nov 26, 2008 at 11:40, Stephen Carr
> <sgcarr at civeng.adelaide.edu.au> wrote:
>> Dear list
>> I am trying to block spams that have the sender forged as a non existent
>> user in our domain but the recipient is a valid email address.
> Kcuuser user -a at REAL
> Kcualias implicit -a at REAL /etc/mail/aliases
> Kcuseq sequence cualias cuuser
> R$* $: $>3 $1 focus on host
> R$+ < @ columbia . edu . > $: $( cuseq $1 $: $1 < NOTCU > $)
> R$+ < NOTCU > $#error $@ 5.7.1 $: 501 Sender unknown
> R$* $@ OK
> Change 'cu' and '@ columbia . edu .' and 'NOTCU' to your own names,
> but using us as an example...
> This tells sendmail, if the MAIL command contains an address with
> '@columbia.edu', look up the local part as an alias and as a user, and
> if neither, reject it '501 Sender unknown', as:
> MAIL from:<blabla at columbia.edu>
> 501 5.7.1 Sender unknown
> This could be extended to more K lookups, and to more domains to
> check. It could probably also be written in a more generalized way
> to be a FEATURE with config variables.
> NOTE: If there is a disclaimer or other legal boilerplate in the above
> message, it is NULL AND VOID. You may ignore it.
> Visit http://www.mimedefang.org and http://www.roaringpenguin.com
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School of Civil and Environmental Engineering
The University of Adelaide
Email sgcarr at civeng.adelaide.edu.au
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