[Samba] Resend of returned email: [3.6.6] Possible to allow password-free read/write access?

David Holder david.holder at erion.co.uk
Thu Apr 16 02:24:57 MDT 2015

Hi Linda,

Just to clarify a little.

At some point your email to the Samba list was relayed by a mail server 
with the IPv6 address:


this address does not have a PTR record.

Since the Samba server is configured with an IPv6 address your IPv6 
enabled server will always connect to it over IPv6. The Samba server 
will look for a PTR record, not find one and then reject the mail.

The solution is to find out which mail server or servers have IPv6 
enabled and that do not have PTR records for their IPv6 addresses. Then 
ensure PTR records for their IPv6 addresses are added. I think that 
turning off IPv6 is a retrograde step, it is better to configure it 
correctly. Take a look at the Received: headers in the original email 
that the Samba server bounces back to you to see where your email was 

Regarding the selection of IPv6 in preference to IPv4, the basic rule is 
IPv6 is preferred over IPv4 but it is much more complex than that. If 
you want the details see RFC 3484 and RFC 6724. Be aware that it is even 
more complex than this as some applications also implement RFC 6555 (and 
that includes email clients) and some operating systems (such as recent 
versions of Windows) also make addition checks (which I think are better 
than RFC6555).

Best Regards,
Dr David Holder CEng FIET MIEEE

Erion Ltd, An Cala, Inverkirkaig, Lochinver, Sutherland, IV27 4LR, UK

Reception: +44 (0)1422 207000

Direct Dial: +44 (0)131 2026317


Registered in England and Wales. Registered Number 3521142
Registered Office: Newtons, 49 Coniscliffe Road, Darlington, County 
Durham, DL3 7EH, UK
VAT Number: GB 698 3633 78

On 16/04/2015 07:40, L.P.H. van Belle wrote:
> Why is someone not setting up an email server conform RFC's
> and seems to be you have an ipv6.. so set the ptr record.
> Hai Linda,
> I do have ipv4 and ipv6 on my server, and im never blocked..
> but i did setup conform all rfcs.. i block servers in the same way.
> so yes, i did set my reverse for ipv4 and ipv6..
> what most people do wrong..
> 1) the hostname must have A and RR (PTR) and MX record.
> 2) the HELO hostname must have a A Record.
> https://tools.ietf.org/html/rfc2821#section-2.3.5
> and IF you server has an ipv6 ip.. it is preffered over ipv4.
> and for that reson, or disable ipv6 in total, or set the hostname also.
> Greetz,
> Louis
>> -----Oorspronkelijk bericht-----
>> Van: samba at tlinx.org [mailto:samba-bounces at lists.samba.org]
>> Namens Linda W
>> Verzonden: woensdag 15 april 2015 23:34
>> Aan: Samba mailing list
>> CC: Gilles; samba-admin at lists.samba.org
>> Onderwerp: [Samba] Resend of returned email: [3.6.6] Possible
>> to allow password-free read/write access?
>> Why would the samba list be looking for a reverse host name
>> via IPV6?   IFAIK I only have an IPv4 addr and reverse
>> addr.  I don't know if the original went to the person
>> in france or not.
>> Anyone else getting  bounces like this?
>> -------- Original Message --------
>> Subject: 	Returned mail: see transcript for details
>> Date: 	Tue, 7 Apr 2015 13:19:19 -0700
>> From: 	Mail Delivery Subsystem <MAILER-DAEMON at Ishtar.hs.tlinx.org>
>> To: 	<samba at tlinx.org>
>> The original message was received at Thu, 2 Apr 2015 13:09:34 -0700
> >from Athenae []
>>    ----- The following addresses had permanent fatal errors -----
>> <samba at lists.samba.org>
>>     (reason: 450 4.7.1 Client host rejected: cannot find your
>> reverse hostname, [2601:9:6901:1000:226:b9ff:fe48:71e4])
>>    ----- Transcript of session follows -----
>> ... while talking to mail.samba.org.:
>>>>> DATA
>> <<< 450 4.7.1 Client host rejected: cannot find your reverse
>> hostname, [2601:9:6901:1000:226:b9ff:fe48:71e4]
>> <samba at lists.samba.org>... Deferred: 450 4.7.1 Client host
>> rejected: cannot find your reverse hostname,
>> [2601:9:6901:1000:226:b9ff:fe48:71e4]
>> <<< 554 5.5.1 Error: no valid recipients
>> Message could not be delivered for 5 days
>> Message will be deleted from queue
>> -- 
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