I have an error message from one of our staff:

This message is a warning that an email you are trying to send has not yet been delivered. You do not have to do anything yet as the email is still queued for delivery.

An email you addressed to email address : -- xxxxxx.xxxxx@xxxxxx.xx.xx

has not yet been delivered. The problem appears to be : -- Communications error

Additional information follows : -- All hosts are unavailable

This condition occurred after 6 attempt(s) to deliver over a period of 1 hour(s).

You will receive a rejection notice after a maximum of 2 days if the email cannot be delivered. If you sent the email to multiple recipients you will receive one of these messages for each one which is still undelivered, otherwise they have been sent.

We are using Windows SBS 2008 and MS Exchange 2007.

What it's mean and what should I do. Please help me, fast response are needed. Thanks


It looks like Exchange has tried to deliver the message to the Mail eXchange servers listed in the recipients domain settings.

For example, if you e-mail me@somewhere.com.au, Exchange does an MX lookup on the domain somewhere.com.au which results in a number of Mail Servers.

Exchange then tries to deliver the mail to the servers in order of priority.

A communications error would indicate that the remote mail server(s) are down for some reason, or have a firewall/antispam technology that's refusing your IP address in it's entirety (if it just refused the message you would get an "Undeliverable" error message.

You can review the server logs inside the Exchange console to see exactly what transpired in the connection.

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