Cry about...
MS-Windows Troubleshooting

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Microsoft Exchange: Unable to deliver the message due to a communications failure

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Symptom:

All outgoing e-mail messages (i.e. all e-mails which are leaving the company but not including e-mails to others in the company) are returned with the following error:

Your message did not reach some or all of the intended recipients

    Subject: ssss
    Sent:    dddd

The following recipients(s) could not be reached:

eeee on dddd
Unable to deliver the message due to a communications failure
The MTS-ID of the original message is: iiii

where:-

ssss	Is the subject line of the returned e-mail.
dddd	Is the date when the message was sent.
eeee	Is the e-mail address of those the message was to be sent to.
iiii	Internal exchange ID of the message.

Cause:

If this is affecting ALL outgoing e-mails then the problem is almost certainly DNS related and indicates a DNS failure.

To confirm this, open a command session on the same server as exchange server is running and enter the following command:

nslookup -type=mx cryer.co.uk

This should run successfully and show mx-dns information for the specified internet domain. An error, similar to:

*** can't find cryer.co.uk: Not implemented

or

*** can't find cryer.co.uk: Non-existent domain

demonstrates that the error is DNS related.

Possible Remedies:

• If the error affects all outgoing e-mails then check the DNS servers. If you can still browse the internet then it is possible that a firewall is blocking MX-DNS requests. Check that your DNS servers are correct and that you can ping them. See also General Network Connectivity Problems.

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These notes have been tested with Exchange 5.5 running under Windows NT4.