This article was previously published under Q324732
Your Exchange server hosts a domain called mycompany.com. When you send a message to any recipient whose e-mail addresses are in a domain such as sistercompany.com, you immediately receive the following non-delivery report (NDR).
Note The recipient may be a contact.
Your message did not reach some or all of the intended recipients. Subject: Subject_line Sent: Date Time The following recipient(s) could not be reached: UserName on Date Time A configuration error in the e-mail system caused the message to bounce between two servers or to be forwarded between two recipients. Contact your administrator. company.com #5.4.6.
Additionally, following error event is logged in the Application log in Microsoft Exchange Server 2003:
Event Type: Error Event Source: MSExchangeTransport Event Category: NDR Event ID: 3020 Description:A non-delivery report with a status code of 5.4.6 was generated for recipient x-ex;/O=OrgnizationName/OU=AGName/CN=RECIPIENTS/CN=recipientName (Message-ID <ID@ServerFQDN>). Cause: A forward loop was detected by the categorizer. This is a common hosting configuration problem caused when someone uses the provisioning tool to create a contact in one organization unit and creates a user in a different organization user that share the same e-mail address. Solution: Verify that you do not have a user in organizational unit and a contact in a different organizational unit that have the same e-mail address.
Note In Microsoft Exchange 2000 Server, you can track NDRs by increasing diagnostics logging to log event ID 756. For more information, click the following article number to view the article in the Microsoft Knowledge Base:
308323 How to configure SMTP transport to log an event 756 to track non-delivery reports
In the error event, 5.4.6 means "Routing loop detected" (RFC1893).
This issue occurs if the local Exchange organization is authoritative for the sistercompany.com domain. Because the local Exchange organization is responsible for mail delivery to @sistercompany.com, the categorizer tries to find locally a recipient for that message. The categorizer does not succeed, and then you receive the NDR.
Consider following two scenarios in which the Exchange organization is authoritative for the sistercompany.com domain.
The This Exchange organization is responsible for all mail delivery to this address check box is selected for the SMTP address @sistercompany.com.
The SMTP address @sistercompany.com was previously the primary SMTP address for the Default Recipient Policy. Additionally, there was a Mailbox Manager recipient policy.
You configure the address @sistercompany.com as a shared address space, and then click to clear the This Exchange organization is responsible for all mail delivery to this address check box.
For more information about how to share address space, click the following article number to view the article in the Microsoft Knowledge Base:
321721 How to share an SMTP address space in Exchange 2000 Server or in Exchange Server 2003
For Scenario 1
Verify whether a recipient policy is in charge of adding or assigning a Simple Mail Transfer Protocol (SMTP) address (to contacts or mail-enabled users) that end in @sistercompany.com.
In the policy properties, select this SMTP address, and then click Modify.
Click to clear the This Exchange organization is responsible for all mail delivery to this address check box.
For Scenario 2
Delete the Mailbox Manager recipient policy that is created before you change the address @sistercompany.com to a shared address.
Re-create the Mailbox Manager recipient policy.
Restart the IIS Admin Service.
If you send a message to a journal recipient, you will receive a 5.4.6 NDR. The journal recipient does not receive e-mail like other users do. When the journal recipient is listed on the recipient list, the categorizer detects a potential loop and then generates an NDR. For more information about message journaling, click the following article number to view the article in the Microsoft Knowledge Base:
843105 Troubleshooting message journaling in Exchange Server 2003 and in Exchange 2000 Server
Additionally, you may also receive a 5.4.6 NDR when you send messages to Microsoft Exchange Server 5.5. For more information, click the following article numbers to view the articles in the Microsoft Knowledge Base:
919087 Users who have mailboxes on a server that is running Exchange 2000 Server receive an NDR message when they try to send e-mail to Exchange Server 5.5 users
272593 Message generates NDR when sent to a Windows NT Server 4.0 recipient represented as contact in Active Directory
For more information about SMTP transport components, visit the following Microsoft Web site: