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Fuhrmanator

No unique hostname found for source?

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Hi there,

My school and its ISP have had some wonderful past experiences with configuring the DNS servers such that it causes problems that are tough to debug.

Right now, when I try to report a spam, SC says that one of the servers can't be trusted, because it doesn't have a unique host name (I suppose that either means it doesn't do reverse DNS properly).

Here's the line from the detailed SC report at http://www.spamcop.net/sc?id=z682460723z81...bd83041296564dz

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3: Received: From Amnesix.uqss.uquebec.ca ([192.77.51.5]) by ns1.etsmtl.ca (WebShield SMTP v4.5 MR1a); id 1097811082122; Thu, 14 Oct 2004 23:31:22 -0400

No unique hostname found for source: 192.77.51.5

ETS received mail from sending system 192.77.51.5

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I used an on-line web tool to reverse DNS 192.77.51.5 and it yields the following:

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Reverse Lookup Results

Host Type Value

5.51.77.192.in-addr.arpa PTR Amnesix.uqss.uquebec.ca

51.77.192.in-addr.arpa NS clouso.risq.qc.ca

51.77.192.in-addr.arpa NS Amnesix.uqss.uquebec.ca

51.77.192.in-addr.arpa NS Asterix.uqss.uquebec.ca

clouso.risq.qc.ca A 192.26.210.1

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The PTR line appears to match what's in the SMTP header -- not sure if that means the reverse DNS is good. But perhaps SC's lookup was different (or worse, the reverse DNS is giving intermittently different results from different places -- this was the kind of problem we were having last year).

Can anyone help me understand where the problem is?

In the mean time, I've stopped reporting spam, since it wants to point to my school's ISP as the source (which I highly doubt).

Thanks!

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Here's the line from the detailed SC report at http://www.spamcop.net/sc?id=z682460723z81...bd83041296564dz

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3: Received: From Amnesix.uqss.uquebec.ca ([192.77.51.5]) by ns1.etsmtl.ca (WebShield SMTP v4.5 MR1a); id 1097811082122; Thu, 14 Oct 2004 23:31:22 -0400

No unique hostname found for source: 192.77.51.5

ETS received mail from sending system 192.77.51.5

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18774[/snapback]

Actually, I think I found the (or perhaps A) problem. I think it may be a bug in Mailhosts caused by a badly configured DNS.

Look at the line 1 in the SC report cited above:

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1: Received: From CREME.ad.etsmtl.ca ([142.137.3.42]) by ns2.etsmtl.ca (WebShield SMTP v4.5 MR1a); id 109781108399; Thu, 14 Oct 2004 23:31:23 -0400

Hostname verified: grenat.etsmtl.ca

ETS received mail from ETS ( 142.137.3.42 )

-----------

Something strange: CREME.ad.etsmtl.ca resolves to 142.137.3.68 and thus is not the same as grenat.etsmtl.ca (142.137.3.42). Furthermore, grenat.etsmtl.ca does not have an AAAA record (which I think may be what's causing the problem in the first place, since it exists in IP4 but not in IP6).

Grenat.etsmtl.ca resolves to 142.137.3.42 (A record) but doesn't resolve in IP6 (AAAA record).

So, if SC does reverse DNS on A and AAAA records, then perhaps that's part of the problem. If it is, it would seem that SpamCop's error message is delayed.

Many things seem screwy on my schools config, so perhaps it could be a combination.

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I do not believe that your second posting has any actual bearing on the problem as the parse seems to have no problem working it way down to the third entry.

What is the relationship between etsmtl.ca ([142.137.251.15]) and Amnesix.uqss.uquebec.ca ([192.77.51.5])

It would appear to me that etsmtl.ca is properly set up in your MailHost Configueration but that Amnesix.uqss.uquebec.ca is not set up.

Should Amnesix.uqss.uquebec.ca be part of your mailhosts?

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Thanks for your reply.

Before I posted, I re-ran the mailhosts setup (add new hosts).

Amnesix is a mail server of the University of Quebec, our school's ISP. The Mailhosts system doesn't propose it as a host when I do a sending.

I still think that the message "no unique hostname" is wrong for the message 3, and should not be ignored as possibly part of the problem.

Is there a way to force mailhosts to include amesix?

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Yes there is a way. But that takes making contact with someone that can. Please see the Pinned items at the top of this Forum for durther details. In particular, the one tagged as "read before posting" ....

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Thanks for your reply.

Before I posted, I re-ran the mailhosts setup (add new hosts).

Amnesix is a mail server of the University of Quebec, our school's ISP. The Mailhosts system doesn't propose it as a host when I do a sending.

I still think that the message "no unique hostname" is wrong for the message 3, and should not be ignored as possibly part of the problem.

Is there a way to force mailhosts to include amesix?

18804[/snapback]

I would agree that the improper configueration of the Amnesix mail server is the problem but it can not be ignored.

The best fix is for the university to correct the mail server configueration.

Deputies may be able to patch your mailhost setup, but that is a poor fix at best.

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