Blocking emails that claim to come from our domain

[Glenn Steen]

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On 07/12/05, Erick Perez <eaperezh at gmail.com> wrote:
> what about MS and postfix?
> where do i implement that?
>
I'm at home on sick-leave (hopfully, just today....), so this is
entirely from memory (and that is a bit flaky at best:-)...
As said, I apply a restriktion on helo and on senders so this might
look something like (in main.cf "#" inserted to show where the lines
are (wrapping))
#
smtpd_helo_restrictions = permit_mynetworks, reject_invalid_hostname,
reject_non_fqdn_hostname, check_helo_access
hash:/path/to/access_map/file
#
smtpd_helo_restrictions = permit_mynetworks,  check_sender_access
hash:/path/to/access_map/file
#
And in the map file, you have a line rejecting your own domain... something like
yourdomain.tld REJECT You are not me...

Then couple that with the recipient maps check (for valid recipients),
and then you can only receive mail from non-spoofing senders to valid
recipients (that part is described well in the MailScanner wiki). You
can, of course, couple these restrictions with any restrictions you
feel are necessary ("man 5 postconf" is a good place to see exactly
what settings you have available)

.... Or did I missunderstand your question?

--
-- Glenn
email: glenn < dot > steen < at > gmail < dot > com
work: glenn < dot > steen < at > ap1 < dot > se

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