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#1 2019-01-24 01:30:49

snorkack
Member
Registered: 2019-01-23
Posts: 2  

Devuan mailing list problem

I subscribed to dng@lists.dyne.org recently and received an error message.  I was able to complete the registration on the web site but the error needs to be resolved or I will not be able to post anything.  An email sent to any address at lists.dyne.org results in the same error.

The error message:
Your message has been delayed and is still awaiting delivery
to the following recipient(s):

dng-owner@lists.dyne.org
(Was addressed to dng-owner@lists.dyne.org)
Message delayed
450 4.7.25 Client host rejected: cannot find your hostname, [65.49.128.26]

No recipients were successfully delivered to.

Reporting-MTA: dns; modus
Received-From-MTA: dns; [192.168.0.2] (unverified [174.238.156.145])
Arrival-Date: Tue, 22 Jan 2019 12:34:31 -0700

Final-Recipient: rfc822; dng-owner@lists.dyne.org
Action: delayed
Status: 2.1.0 (Success - addressing: no additional status information available)
Diagnostic-Code: smtp; 450 4.7.25 Client host rejected: cannot find your hostname, [65.49.128.26]

Received: from [192.168.0.2] (unverified [174.238.156.145]) by modus
(Vircom SMTPRS 6.3.119.21572/5271.7.4.) with ESMTP id <B0821464405@modus> for <dng-owner@lists.dyne.org>;
Tue, 22 Jan 2019 12:34:31 -0700
X-Modus-BlackList: 174.238.156.145=OK;fred@blakemfg.com=OK
X-Modus-RBL: 174.238.156.145=OK
X-Modus-Trusted: 174.238.156.145=NO
X-Modus-Spam-Version: 6.3.119.21572/5271.7.4.
X-Modus-Audit: FALSE;0;0;0
Message-ID: <5C4770A5.5010207@blakemfg.com>
Date: Tue, 22 Jan 2019 12:36:05 -0700
From: Fred <fred@blakemfg.com>
User-Agent: Mozilla/5.0 (X11; Linux i686; rv:31.0) Gecko/20100101 Thunderbird/31.1.1
MIME-Version: 1.0
To: dng-owner@lists.dyne.org
Subject: possible mailing list problem
References: <B0821311430@modus>
In-Reply-To: <B0821311430@modus>
X-Forwarded-Message-Id: <B0821311430@modus>
Content-Type: multipart/mixed;
boundary="------------000001020709010903050907"
End of error message.

Would someone please forward this to dng-owner@lists.dyne.org and ask that I be advised how to resolve the issue?

Best regards,
Fred

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#2 2019-01-24 02:39:44

golinux
Administrator
Registered: 2016-11-25
Posts: 1,675  

Re: Devuan mailing list problem

That list is moderated.  Did you try to post?  No email ever arrived to moderation.  That's how I know when someone new has registered.

I think your DNS might not be set up correctly because your "server DNS address could not be found.
DNS_PROBE_FINISHED_NXDOMAIN"

PS.  It would probably be a good idea to remove your email address from that post.

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#3 2019-01-24 06:37:53

RickMoen
Member
From: preferably on a cruise ship
Registered: 2019-01-24
Posts: 10  
Website

Re: Devuan mailing list problem

Fred, as a disclaimer, I'm unfortunately not a lists.dyne.org admin, and in particular have no access to its SMTP logs, which would be handy in this case.  So, I don't speak for administration, and have no insight into host configuration.  However, I'm a sysadmin (and DNS admin) elsewhere, so may be able to help.

I infer that lists.dyne.org (IP 195.169.149.119) was, as of the time of that delivery attempt, tempfailing your delivery attempt (thus the 450 SMTP error code -- 45x being temporary failures and 55x being permanent) because your sending domain's DNS is dysfunctional.  Observe:

$ dig -t ns blakemfg.com
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 29626
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 0

;; ANSWER SECTION:
blakemfg.com.           3600    IN      NS      ns2.iosaz.net.
blakemfg.com.           3600    IN      NS      ns1.iosaz.net.
$

See the "AUTHORITY: 0"?  That's because ns2.iosaz.net and ns1.iosaz.net are not declared authoritative in your registrar records (which results in them being listed as NS records for your blakemfg.com domain in the parent .com zone).  Instead, the parent zone lists your authoritative nameservers as ns1.aspect1.net and ns2.aspect1.net.  Rule of thumb:  Always change in unison the in-zone NS lines and the parent-zone NS lines.  They must always match.

While I'm at it, a couple of other comments:

1.  The EXPIRE value in your SOA record is out of spec (too low).  You have 604800 seconds.   RFC1912 suggests a value between 1209600 and 2419200.

2.  It's contrary to your interests (helps probing your software) to allow your nameservers to give accurate answers to the CHAOS class bind.version query.

$ dig -c CHAOS -t txt version.bind @ns1.iosaz.net +short
"9.8.2rc1-RedHat-9.8.2-0.23.rc1.el6_5.1"
$

 
Since you're running BIND9 ;-> , I can suggest a conf file snippet to make it give your preferred answer queries for the version.bind synthetic hostname (using my own linuxmafia.com server as an example).  My own preferred answer is to use the Leslie Nielsen joke from 'Airplane!':

options {
        directory "/var/cache/bind";
        version     "Shirley, you're joking";
        hostname    "ns1.linuxmafia.com";
        //server-id is essentially redundant to hostname, default is none
        //server-id  none;
       // [omit other lines from this section]
};

3.  It is slightly problematic that your mail server's forward resolution name (mail.blakemfg.com) doesn't match the reverse-DNS resolution of the resulting IP address (65.49.128.26):

$ dig -t mx blakemfg.com +short
10 mail.blakemfg.com.
$ dig -t a mail.blakemfg.com +short
65.49.128.26
$ dig -x 65.49.128.26 +short
mail.iosaz.net.
$ 

To my knowledge, no RFC requirement so far requires a forward/reverse match (called 'forward-confirmed reverse DNS'), but in these days of twitchy spam-rejecting heuristics, it's in your interest to follow best practices or domains may treat your mail suspiciously or reject it.

Edited to add:

4.  Is there a particular reason why there is no 'A' record at all for FQDN 'blakemfg.com'?  That's a little wacky, and some accepting SMTP systems may choke on that, too.

Last edited by RickMoen (2019-01-24 09:36:41)


Rick Moen
rick@linuxmafia.com

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#4 2019-01-24 14:07:55

snorkack
Member
Registered: 2019-01-23
Posts: 2  

Re: Devuan mailing list problem

Hello,
My ISP doesn't offer email service so I pay another company to provide email and domain hosting.  I can try asking them to correct the issues you mention.

golinux
I didn't try to post because my reply to the registration email and to dng-owner both resulted in delay/delivery failure notices.  It didn't make any sense to try posting until the problem was corrected.

Thank you both for your responses.
Best regards,
Fred

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#5 2019-01-24 15:34:57

xinomilo
Member
Registered: 2017-07-02
Posts: 68  

Re: Devuan mailing list problem

reading at the headers, i think there might be something wrong with outgoing (SMTP) settings. can you double check (outgoing server/port/auth) ?

(or ask hosting provider for correct settings..)

Last edited by xinomilo (2019-01-24 15:35:30)

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#6 2019-01-24 16:01:24

golinux
Administrator
Registered: 2016-11-25
Posts: 1,675  

Re: Devuan mailing list problem

snorkack wrote:

Hello,
My ISP doesn't offer email service so I pay another company to provide email and domain hosting.  I can try asking them to correct the issues you mention.

Rick is an admin ninja so I'm pretty sure this has something to do with your ISP's config.  This is the first time something like this has popped up since the forum started.  Is there any particular reason you chose that ISP?  When I see .aspx, I run the other way (personal prejudice). . . .

I didn't try to post because my reply to the registration email and to dng-owner both resulted in delay/delivery failure notices.  It didn't make any sense to try posting until the problem was corrected.

Makes sense. It might be some consolation to know that your registration was successful and you are in the user list so you should be able to post once your ISP gets it together.

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#7 2019-01-24 21:09:37

PedroReina
Member
From: Madrid, Spain
Registered: 2019-01-13
Posts: 74  
Website

Re: Devuan mailing list problem

golinux wrote:

When I see .aspx, I run the other way

Me too, and as fast as I can.

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#8 2019-01-24 21:11:48

RickMoen
Member
From: preferably on a cruise ship
Registered: 2019-01-24
Posts: 10  
Website

Re: Devuan mailing list problem

snorkack (Fred), now that I've slept on this, and also having seen your explanation that what we're seeing is ISP follies from a firm paid to host your domain's e-mail and DNS, I think I can help more.

On reflection, point #4 I added as afterthought yesterday is the immediate reason for the 45x tempfails.

450 4.7.25 Client host rejected: cannot find your hostname, [65.49.128.26]

As I mentioned, '450' is a classic tempfail, i.e., delivery is being refused at the moment, but not definitively and the mail may be accepted later upon redelivery attempt.  These three-digit SMTP error codes were found (if I recall correctly) by the Internet Engineering Task Force to need further elaboration, so the N.NN.NN status codes like 4.7.25 were added.  4.7.25 is part of the "4.X.X " group of Persistent Transient Failure SMTP error status codes, but we don't even need to look up what it means because the full explanation is right next to that:  "cannot find your hostname, [65.49.128.26]"

Yesterday, I was slow to make the connection, but it's very literally saying your mail is being tempfailed because mail.dyne.org has the (reasonable) expectation that your hostname's DNS name (blakemfg.com) would resolve, but it doesn't.  65.49.128.26 is the IP address of the ISP host handling your mail.  There is a regular 'A'-type DNS record for mail.blakemfg.com, but not one for blakemfg.com itself.  This is a very peculiar but damaging administrative error on your ISP's part.  Let me explain why:

We're several decades into a war between spammers and sysadmins.  One big weapon we sysadmins have is enforcement of DNS and SMTP technical standards.  Spam characteristically ignores a bunch of those standards and just spews out poorly-compliant bitstreams to see who'll accept them.  Rejecting standards-ignoring mail is thus a highly effective antispam heuristic.  So, increasingly, mail-sending domains must be competently administered or they'll get doors slammed in their faces.  In this case, you got a gently closed door with a nice note saying 'Hey, you're welcome to try again but need to fix this problem.'  And what to fix was right there.

That leaves you with a potentially serious problem, because, frankly, all the DNS misconfigurations I mentioned[1] are things I'd fire (well, put on probation) a junior sysadmin for at any place that does e-mail and DNS for, y'know, a freakin' living.  You can certainly ask the ISP to fix those issues, but expecting them to suddenly find their mislaid competence just because you pointed out some abject failures at doing your DNS seems... optimistic.  Sure, try that if you wish, but then check that they fixed all the problems, and have a Plan B in case they keep screwing up because they just aren't good at the job.  Personally, I'd be treating them a bit like a sandwich shop that served me a meatball sandwich with a layer of dirt in it.

So, I'd be looking in the Yellow Pages under "ISPs that are not named Internet Operating Services of Arizona LLC". 

Also, as a Linux user generally and as domain owner, you may find getting to be really good at use of /usr/bin/dig and studying DNS administration really useful in keeping hosting companies honest and understanding what's going on.  There's a nice (and free-as-in-gratis) online book:  http://www.zytrax.com/books/dns/  (For one thing, consider:  Fluency with 'dig' will let you check up on your provider and make sure the current sorts of woes don't recur.)

[1] Except for the one where your mail server's forward resolution name (mail.blakemfg.com) doesn't match the reverse-DNS resolution of associated IP address 65.49.128.26.  (As mentioned, as a separate problem, they did omit a forward resolution DNS record for blakemfg.com.)  Your explanation makes clear that IP address 65.49.128.26 is a machine used for shared hosting.  The ISP probably virtual-hosts hundreds of customer domains from that IP.  Each customer domain forward-lookups to IP 65.49.128.26:  In DNS, you can have an arbitrarily large number of forward-lookup "A" records all pointing to the same IP -- but the IP can reverse-resolve to only a single fully qualified domain name (FQDN).  In this case, they've understandably chosen to have it resolve to the ISP's own FQDN,
mail.iosaz.net. 

Fortunately, to my knowledge, even the most militantly antispam SMTP servers don't require forward/reverse exact match, albeit many insist that the delivering IP reverse-resolve to something, or else will refuse mail from that IP.  (And your IP does reverse-resolve to something.)

Last edited by RickMoen (2019-01-24 23:43:22)


Rick Moen
rick@linuxmafia.com

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