ot a bit: sendmail and TO mx not found
Peter Farrow
peter at farrows.org
Tue Sep 2 16:49:23 IST 2014
Continuing further, as my previous reply you only try the secondaries in
the event of a temporary error. A timeout includes a temporary error,
but a failure to resolve_*/does not /*_:
The lookup first attempts to locate an MX record associated with the
name. If a CNAME record is found, the resulting name is processed as
if it were the initial name. If a non-existent domain error is
returned, this situation MUST be reported as an error. If a
temporary error is returned, the message MUST be queued and retried
later (seeSection 4.5.4.1 <http://tools.ietf.org/html/rfc5321#section-4.5.4.1>). If an empty list of MXs is returned,
the address is treated as if it was associated with an implicit MX
RR, with a preference of 0, pointing to that host.
On 02/09/2014 16:33, Rick Cooper wrote:
> rfc5321 does not say that, as I read it. It says:
> The lookup first attempts to locate an MX record associated with the
> name. If a CNAME record is found, the resulting name is processed as
> if it were the initial name. If a non-existent domain error is
> returned, this situation MUST be reported as an error.
>
> You cannot report as error and continue on with delivery, this doesn't mean log an error it means
> cease and report as error ( not even defer). Assuming this is what you are speaking of the correct
> thing to do would be to try the primary and (assuming it returned a cname) stop the delivery attempt
> when it cannot be resolved.
>
> ------------------------------------------------------------------------
> *From:* mailscanner-bounces at lists.mailscanner.info
> [mailto:mailscanner-bounces at lists.mailscanner.info] *On Behalf Of *Joolee
> *Sent:* Tuesday, September 02, 2014 10:37 AM
> *To:* MailScanner discussion
> *Subject:* Re: ot a bit: sendmail and TO mx not found
>
> rfc5321 section 5 indicates that Sendmail /should/ try the server(s)
> to whom the alternative MX records point. It shouldn't try all
> multihomed A records pointed to by a single MX record (although,
> that's not exactly what the RFC says) but that's not the case here. So
> the question still is, why doesn't Sendmail try the alternative MX
> records?
>
>
> On 2 September 2014 14:39, Peter Farrow <peter at farrows.org
> <mailto:peter at farrows.org>> wrote:
>
> If the primary MX does not resolve , sendmail will not try a
> lesser MX record, because the best option is unresolvable, so it
> will return the message after checking and appending any search
> parameters given in /etc/resolv.conf.
>
> This behaviour is by design, and you are trying to fix a problem
> which is inherently not yours to solve.
>
> If the primary MX does not resolve : The domain is broken - so why
> try and work around that?
>
>
>
>
>
>
> On 02/09/2014 13:19, ja at conviator.com <mailto:ja at conviator.com> wrote:
>> hi
>> its a bit OT but I hope its OK anyway. We are also using
>> Mailscanner as outbound scanner and see a problem that I cannot
>> figure out - probably some setting im missing.
>> sometimes "we" send emails to a domain where the primary MX
>> record does not resolve. I would have expected that sendmail
>> would just try the next but instead it resolves to
>> mxrecord.name.OURDOMAIN.COM <http://mxrecord.name.OURDOMAIN.COM>
>> (I think) - it seams it appends our domain and then tries this
>> server and this server says "no thanks" so the delivery fails.
>> I tried to lookup the MX myself using the same nameserver as the
>> mailscanner server is using - this fails so its not the DNS
>> server that appends something to make it resolveable or gives out
>> a standard IP.
>> I also checked the resolve file to check that there is not search
>> setting that would make it search our domain for a valid IP/lookup.
>> how can I stop this behavior and make it try the next MX in line?
>> best regards
>> Jan
>>
>> --
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>>
>>
>> --
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>>
>> Peter Farrow
>> avatar
>> ______________________
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>>
>
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> Peter Farrow
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> ______________________
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