We have looked at the settings within Exchange Server and tried changing outbound security settings to allow the account to be authenticated, but to no avail. If you could shed any light on this, it would me much appreciated.
Two things spring to my mind based on your description. First, this could be a problem with your server's ability to categorize and route the message. Second, it could be that the target organization is filtering mail from your domain. In either case you will not receive any NDRs.
If you have not enabled message tracking on your Exchange server, then you need to do so immediately. This will allow you to use the Message Tracking Center that is included in the Exchange System Manger to track the message from the point in time it is submitted to the information store, to the point at which it leaves your organization. So, if the problem is on your server, you will be able to find it.
If, after enabling message tracking, you determine that the message has been successfully categorized, routed and sent to an external host, then you can start to look at whether or not your domain is being filtered by the target organization. Specifically, a "Sender Filter" in Exchange 2000/2003 has the unique ability to filter a message, place it in an archive folder and not to notify the sender or the intended recipient.
For more information on troubleshooting mail flow problems, including how to use the MTC, see General troubleshooting for transport issues Exchange 2000 Server and in Exchange Server 2003.
MEMBER FEEDBACK TO THIS ASK THE EXPERT Q&A:
I am having a similar problem. I work for a company that still uses Exchange 5.5 with a mix of Windows 2000 and NT4 servers. Lately I have gotten some complaints about outgoing e-mail not getting received at the other end. I am having a hard time finding information on how to turn on the necessary diagnostic logging for Exchange 5.5, since it is no longer supported by Microsoft.
Can you point me to somewhere that would have information about how to troubleshoot outgoing SMTP traffic with Exchange 5.5?
The fact that Exchange 5.5 is no longer being supported has in some way impacted every organization still running 5.5. However, Exchange 5.5 is still an extremely well documented product and Microsoft did not systematically remove all knowledge base articles from their support site or TechNet.
Another good thing about the problem you are having is that SMTP is an open standard. The troubleshooting techniques are somewhat universal. The tricky part is finding out how to do it in Exchange 5.5. I would start with the article "Verifying the configuration of an Internet mail service." You can also find answers to your Exchange 5.5 problems from articles that may seem unrelated, such as "How to troubleshoot Exchange Server 5.5 behind Proxy Server 2.0." One of the links in this article includes instructions on how to enable diagnostic logging: "How to obtain additional information from Internet mail or unsolicited commercial e-mail."
Unfortunately, while you can capture the command/reply process between your server and external SMTP host, you may need to enlist the administrator of the target organization's help in identifying why the e-mail is not reaching the target recipient. Keep in mind that security devices, like spam filters, could ultimately be the culprit here.
—Richard Luckett, Spam and Security Expert
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