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Delivery expired - DNS Soft Error – ServFail (1000 Points!)


I opened this question under the general topic of "Email/GroupWare" but have had no responses.  Therefore I am opening the same question under the Exchange Server topic.  I will award the points from both to whoever is able to help me resolve this problem ASAP!

We are experiencing a strange problem whereby one of our customers seems to be unable to send us emails.  The error message they get back is as follows:

Final-Recipient: rfc822;xxxxxxx@xxxxx.com
Action: failed
Status: 5.0.0 (permanent failure)
Diagnostic-Code: smtp; 5.4.7 - Delivery expired (message too old) 'DNS Soft Error looking up xxxxx.com (MX) while asking Error was: ServFail' (delivery attempts: 0)
Reporting-MTA: dns; ironport.ccccc.com

Has anyone had any experience in solving this problem?

Is this something on our end or the customer's end?  (It appears they have setup their own DNS servers.)



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1 Solution
Chris DentPowerShell DeveloperCommented:


I should note first that you can't award more than 500 points for a single question, it's against the member agreement. I'll dig through the help pages and find where it's stated if you need it. For anyone else participating the link to the original is here:


Given that there are no posts there you may consider closing it and just keeping this one open. This is to prevent duplication of effort more than anything else.

Anyway... all that aside:

One of the better first places to stop is www.dnsreport.com. It will allow you to run a series of tests against a domain and help point out any serious problems - including checks of the Mail Server and MX records.

It's a great idea to run this against your own domain to see if there any oddities that may cause the delivery failure.

If DNSReport shows no errors, and no one else has trouble sending to you then the troubleshooting of the problem should really begin on the senders end - after all, they can't find your mail server.

grhelmAuthor Commented:
Sorry, I did not realize that.  I have deleted the other question and therefore this question is only worth a maximum of 500 points.

I tried the DNSREPORT and as far as the MX and Mail result all PASSed except 3 that had WARN's.  I don't believe these have any impact on the mail service.  

Not only can the customer NOT send email to us, but we are unable to send to them also.  (I will attempt to add some additional information on this when I get it from our users.)  They are able to forward messages to another online account (e.g. - hotmail) without any problems and we are able to receive from others without any problems...
Chris DentPowerShell DeveloperCommented:

What error are you bumping into while trying to send mail to them?

You can do the same thing with their domain as you did with yours and stick it in DNSReport. As before that will point out and errors that may stop people mailing them.

If you get a chance it would be a good idea to test out sending a mail to them through the command line. Something like this from your Mail Server would do:

C:\> nslookup
> set type=mx
> recipientsdomain.com
> exit

That will give you a mailserver you should be able to send to. Then:

C:\> Telnet mailserver.recipientsdomain.com 25

At this point you should get a message back from their mailserver identifying itself. Telnet from the command line isn't at all forgiving of typing mistakes, so any odd error messages will be most likely caused by use of the backspace key.

Each command you type in here should give you a 250 Message indicating it's happy. If it gets too messy you can use the RSET command which will start everything over again. At the Telnet Prompt Type:

helo yourdomain.com
mail from: you@yourdomain.com
rcpt to: someone@recipientsdomain.com
Subject: Testing


The Enter, then the . then the Enter will submit the message into the queue on that server.

This will help point out any clear problems with the recipients domain - for example you might not even be able to get their MX record - which would be a problem. Or their server might refuse to accept mail from you - and it'll tell you.

It's entirely possible the two problems are related. It's possible their mail server is rejecting mail because it can't resolve your domain name (for whatever reason). If DNSReport didn't come up with any errors then this really does need to be looked at on the customers site as well.

grhelmAuthor Commented:
I just checked with the user and this "magically" started working this morning.  I have asked that she check with the customer to see if they made some changes on their end this morning, but they are a very large organization and it is unlikely that we will get an answer anytime soon.

Therefore, I will award the points to you as it seems this has resolved itself on its own.  If I do get a response as to any changes made on the customer’s end, I will post them here.
Chris DentPowerShell DeveloperCommented:

No problem... at least it's working for the time-being.

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