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DNS/MX Issue Question

Posted on 2011-09-15
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Last Modified: 2012-05-12
We have a client that is not receiving emails that our webserver is sending to them.  

Our server is not blacklisted, nor is it an SPF issue.  Emails are being delivered to every domain except for them.

I'm talking to their IT guy right now - and he's saying that his suspicion is (because there is no record that the emails have ever hit their server) that we are not sending to the right MX record for their domain.  

Now - I'm not really a DNS/Server guy (my thing is software) - but that doesn't make sense to me.

Correct me if I'm missing something...

We (my server) have nothing to do with the MX record of your server.  Nor do we have any control over what MX record is being sent to.  That's handled specifically by your DNS.  As such, we have no control over how the email is routed...as that's controlled specifically by your nameserver/DNS records you've set.

Isn't that correct?  Or - is there something we can do on our end that I'm somehow missing?
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Question by:erzoolander
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by:uescomp
ID: 36543250
Well one this is for sure, they have to have a static because if its dynamic and their DNS changes they will not get anything.  The MX record I believe is held by whoever has the domain.
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by:davealford
ID: 36543260
You could have a corrupt DNS cache entry on the webserver sending the form.

If its a Windows server you can try ipconfig /flushdns

Also if a Windows server, try using

nslookup
set type=mx
"domain name"

Replace "domain name" with the target domain.
That should show what the server is sending to
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by:danlein
ID: 36543296
I agree as long as the address is correct, you have nothing to do with their MX records, have you tried to reply to an e-mail they sent? And if that does not work someone may have an enterprise rule issue with an anti-virus or firewall or possibly the mail server. Are you using exchange or POP, is he using a mail server or POP?
   
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by:erzoolander
ID: 36543380
They use microsoft forefront.

With respect to a corrupt DNS - we're on a linux box - and when I do an NSLookup - it shows the correct mail exchanger for them.
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Ross-C earned 500 total points
ID: 36543410
I agree with you and danlein it's probably due to a firewall or email some kind of email filtering.
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by:davealford
ID: 36543537
can you telnet to the mx record on port 25 from the server?
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by:uescomp
ID: 36575546
Is the port open to allow incoming mail on your router?
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