Mailinglist Archive: opensuse (3337 mails)

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Re: [SLE] Stopping spam to postmaster@ account?
  • From: Sandy Drobic <suse-linux-e@xxxxxxxxxxxxxxxxxxxxxxx>
  • Date: Tue, 04 Apr 2006 20:21:49 +0200
  • Message-id: <4432B93D.9050600@xxxxxxxxxxxxxxxxxxxxxxx>
Carlos E. R. wrote:
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The Tuesday 2006-04-04 at 17:34 +0200, Sandy Drobic wrote:


That is the only header line you can trust: it has been added by your postfix
server. And that is telling you that your server has accepted the mail from a
client that announced itself in HELO as "PC01" with the IP 219.142.253.248.
Furthermore that IP has no Reverse DNS so Postfix regards the hostname as
"unknown".

dig -x 219.142.253.248 +short

gives an empty result, which means it has no reverse DNS entry.


But "whois" gives some info:

netname: CHINATELECOM-BJ
country: CN
descr: CHINANET beijing province network

Unfortunately Postfix does not care about whois info. (^-^)

I could also mention the restriction "reject_unknown_hostname", although only postmaster that really hate spam more than they love their wanted mail would consider to apply that restriction. (^-^)

If anyone is thinking about that restriction I strongly advise to test it first with "warn_if_reject reject_unknown_hostname". That will log a warning but not actually reject the mail. You will probably find out that there are a lot of badly misconfigured "professional" mailservers. :((

3. Reject based on ip address with a RBL that blocks those IPs. Be prepared to
whitelist some clients that are wrongly listed in these RBLs. That is the
reason why such RBLs are chancy.


And also some people like me who send email direct.

True, many here on this list privately use their own server at home. I do that as well, though I am lucky to have the option to use the mailserver of my provider as relay if some ISP rejects mails from dynamic ip addresses.

Sandy
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