Bill
W B Hacker wrote:
> Frank S. Bernhardt wrote:
>
>> Good day.
>>
>> This isn't really an EXIM problem but I'm not sure what to do.
>>
>> I have a customer that can't send e-mails to two of his suppliers in
>> China in that his e-mails keep bouncing back with a '452 Invalid sender'
>> messages.
>>
>> I tried a telnet to mail.promexsh.com 25 and as soon as I did:
>>
>> mail from: phil@???
>>
>> I immediately got the 452 error.
>>
>>
>
> I'll call thei possibility TWO.
>
> pintar.ca resolves to IP 209.250.128.44
>
> but IP 209.250.128.44 resolves to webhost02.pathcom.com
>
> The same telnet from one of my Hong Kong servers, HELO'ing with the hostname in
> the rDNS, succeeds to the next step:
>
> ========
>
> conducive# telnet mail.promexsh.com 25
>
> Trying 218.30.103.130...
>
> Connected to mail.promexsh.com.
> Escape character is '^]'.
> 220-W E L C O M E T O H I C H I N A S M T P S E R V I C E !
> 220 mxvip2.hichina.com ESMTP server (quarkmail server - version 1.2.1) ready at
> Thu, 20 Jul 2006 01:12:27 +0800
>
> helo conducive.org
>
> 250 mxvip2.hichina.com Hello conducive.org
>
> ^]
> telnet>
> quit
>
> 221 mxvip2.hichina.com Out
> Connection closed by foreign host.
>
> ========
>
> Perhaps the distant end has an overly strict HELO match rule in place.
>
> What happens if you try to HELO as webhost02.pathcom.com?
>
>
>> This happens as well with the mail.jinmao.com server.
>>
>>
>
> Likewise - it talks to a server with HELO / rDNS match:
>
> ========
>
> conducive# telnet mail.jinmao.com 25
>
> Trying 218.244.143.23...
>
> Connected to mail.jinmao.com.
> Escape character is '^]'.
> 220-W E L C O M E T O H I C H I N A S M T P S E R V I C E !
> 220 mxdxt3.hichina.com ESMTP server (quarkmail server - version 1.2.1) ready at
> Thu, 20 Jul 2006 01:14:57 +0800
>
> helo conducive.org
>
> 250 mxdxt3.hichina.com Hello conducive.org
> ^]
> telnet>
> quit
> 221 mxdxt3.hichina.com Out
> Connection closed by foreign host.
>
> ====
>
>
> Well - they *may* be more strict about HELO/DNS match on arrival than they are
> themselves on departure, and/or they use separate servers for incoming and
> outgoing - not at all uncommon, and not always doen with the best of DNS
> entries. The banner alone is not conclusive.
>
> But if 'job ONE' is to just get your users' mail to be accepted by them, all you
> *may* need to do is insure your rDNS and HELO match on your own server.
>
> Easy to try that anyway.
>
>
It did turn out to be a DNS issue that was solved by setting up an MX
record for the sending smtp server 'pintar.pintar.ca' along with a
corresponding reverse DNS record.
I was sure that there was a CNAME record for pintar.pintar.ca but I
think it was lost when they moved to a new loaction (with the subsequent
new IP address). I didn't think they needed an MX record because emails
are only sent from pintar.pintar.ca but email is received via the ISP's
server, which does the virus and spam scanning.
Learn something new every day.
A special thank you to Bill who pointed me in the right direction.
Cheers.
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