Exchange 2003 Event ID 3030 - Status Code of 5.6.1

I have a small distribution group email address setup in my exchange server that has three internal employee as members and one "contact" record member.  The contact record is a contractor employee who needs to be copied on these emails (but obviously has a different email address than employees of our company).  On certain occasions, especially with one particular customer, when an email is sent to the distribution list, the contractor complains that he never received the email, even though the internal employees do get the email.  When I go to message tracking on the exchange server, I see that there is a NDR generated (though it does not indicated why or to who).  When I look in the exchange servers Event Log (Application), I can see that when this email comes in, there is an error generator saying:

Event ID:  3030
Category:  NDR

A non-delivery report with a status code of 5.6.1 was generated for recipient rfc822; (Message-ID <>)

The NDR is only occasionally generated with certain customers (always it seems with this particular customer) for the contractor's email address.  Yet, the email is successfully delivered to our internal employees all the time.  Any idea on why this contractor's email address is sometimes rejected?  If have sent numerous test emails from my personal yahoo email account to this distribution list email, and it always successfully reaches the contractor employee.  Even other customers are successful, but a few are not.
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Nick RhodeIT DirectorCommented:

Not entirely sure on how you created the account.
Hypercat (Deb)Commented:
I had to do a little research on this issue because I haven't seen a status code of 5.6.1 for a long time.  Apparently it has something to do with 8-bit MIME format and the receiving server rejecting the message because that server doesn't support 8-bit MIME format.

I know this is not a lot of help, but it somewhat explains why the message would be rejected sometimes and not other times.  It's not the contractor's address that's the problem at all, it's the receiving email server that is rejecting the message because of a format issue.  You could assume that on the receiving end there is more than one SMTP server and one (or more) of them doesn't support 8-bit MIME and the message only gets rejected if it happens to hit that server.  

Unfortunately, I don't know of any way to troubleshoot this from the sender end. One thing you could try to resolve the issue would be to send the messages in plain text format and see if that goes through reliably.
jbobstAuthor Commented:
This 8-bit thing...I saw that on a few searches, but I didn't understand it.  So could it be that the client who is initially sending this email has their email in some sort of older format and our contractors email server doesn't like this format?  I just don't know where to troubleshoot this unfortunately.  I suppose I should start by contacting the hosting company of the contractor's email server and see if they have any advice.

NRhode, I created my contact record just like the person in the article did.
Hypercat (Deb)Commented:
It could be what you suggested, or it could be something that's happening during the redirection of the email through your email server.  I assume that the original email is addressed to "" and that one of the members of that distribution list is a contact with an email ""  There are a couple of things you could try that might work better.

First, you could give the contractor an internal email address "" (i.e., a regular mailbox on your server), and then set that as the member of the distribution list. Then, set up an automatic forward on that AD account of all email to "".  I know that sounds awkward, but it might work more reliably. One advantage of this method is that you could have someone monitor the internal mailbox and you would see if an NDR is generated, and then could try to re-send the message to the contractor manually.

Another thought would be to remove the contact from the distribution list entirely, and have it forwarded automatically through one of the other internal email addresses.  IOW, set up a rule on one of the internal mailboxes in Outlook to forward all mail received by that distribution list to the contractor's contact email address.

I'm not sure either of these things would resolve your issue, but you could give them a try.

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jbobstAuthor Commented:
hypercat, great suggestions!  I removed his contact from the distribution lists and gave him a domain account instead (that in turn forwards to his real email address).
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