You receive a non-delivery report after you send an e-mail message to an Exchange 5.5 recipient

When a user whose mailbox resides on a server that is running Microsoft Exchange 2000 Server or Exchange Server 2003 sends an e-mail message to a Microsoft Exchange Server 5.5 recipient, the sender may receive a non-delivery report (NDR) that is similar to the following:When this behavior occurs, an event that is similar to the following is logged in the application event log:

Event Type: Warning
Event Source: MSExchangeMTA
Event Category: X.400
Event ID: 290

Description:
A non-delivery report (reason code unable-to-transfer and diagnostic code unrecognized-OR-name) is being generated for message C=Country;A= ;P=Domain Name;L=Server Name-040123182131Z-19. It was originally destined for DN:CN=User Name,CN=Container Name,OU=Organizational Unit,O=Organization (recipient number 1), and was to be redirected to . [MTA DISP:RESULT 20 136] (12)

Note If the Exchange 5.5 recipient sends an e-mail message to a user who has a mailbox on a server that is running Exchange 2003 or Exchange 2000, the message is delivered successfully.

This behavior may occur if all the following conditions are true:

• Your mailbox is located on a server that is running Exchange 2000 or Exchange 2003.
• When you installed Exchange 2000 or Exchange 2003, you joined the Exchange server to an existing Exchange 5.5 site.
• There is a dot (.) in the server name of the Exchange 5.5 server where the mailbox of the recipient is located.

To work around this behavior, choose one of the following methods.

Method 1: Move all Exchange mailboxes to a different Exchange 5.5 server

Move all Exchange mailboxes from the Exchange 5.5 server that has a dot in the server name to another Exchange 5.5 server that does not have a dot in the server name. To do so, follow these steps on the Exchange 5.5 server that has a dot in the server name:

1. Click Start, point to Programs, point to Microsoft Exchange, and then click Microsoft Exchange Administrator.
2. Connect the Exchange Administrator program to the other Exchange 5.5 server.
3. Click the mailbox or the group of mailboxes that you want to move.
4. On the Tools menu, click Move Mailbox, click the Exchange 5.5 server that you want, and then click OK.
5. Repeat steps 3 and 4 to move all mailboxes.

Method 2: Move all mailboxes to a server that is running Exchange 2000 or Exchange 2003

To move all mailboxes on the Exchange 5.5 server that has a dot in the server name to a server that is running Exchange 2000 or Exchange 2003, follow these steps:

1. Click Start, point to Programs, point to Administrative Tools, and then click Active Directory Users and Computers.
2. Locate the users whose mailboxes reside on the Exchange 5.5 server.
3. Select the user mailboxes that you want to move.
4. Right-click the selection you made in step 3, and then click Exchange Tasks.
   
   This process initializes the Exchange Tasks Wizard. The Exchange Tasks Wizard guides you through the process of moving the mailboxes to the server that is running Exchange 2000 or Exchange 2003.
5. Repeat steps 2 through 4 until all the Exchange 5.5 mailboxes are moved.

Method 3: Remove the server that is running Exchange 2003 or Exchange 2000 from its current administrative group, and then install it in another administrative group.

Although Microsoft does not recommend this method, you can remove the server that is running Exchange 2003 or Exchange 2000 from the current administrative group and then install it in a different administrative group that does not have an Exchange 5.5 server that has a dot in the server name.

To do this, use the bootstrap method. You only have to use the bootstrap method if you have to add an Exchange 5.5 server to a new administrative group that has no Exchange servers in it.

If there is an existing administrative group that contains at least one Exchange 5.5 server, and none of the Exchange 5.5 servers in that administrative group have a dot in the server name, the server that is running Exchange 2000 or Exchange 2003 can join that administrative group.

Note If the Exchange 5.5 server that has a dot in the server name is configured as a bridgehead server, set the directory replication connector to an Exchange 5.5 server that does not have a dot in the server name.

For additional information about how to move the directory replication connector for an Exchange 5.5 server, click the following article number to view the article in the Microsoft Knowledge Base:

After you have verified mail flow and directory replication with the Exchange 2003 or Exchange 2000 server that you installed to a different site, use Exchange Mailbox Merge Wizard (Exmerge.exe) to move all the mailboxes. You can use Exmerge.exe to move all the mailboxes from the server that is running Exchange 2003 or Exchange 2000 and that is in the site that has an Exchange 5.5 server that has a dot in the server name. Use Exmerge.exe to move those mailboxes to the site that does not have an Exchange 5.5 server that has a dot in the server name.

For additional information about moving mailboxes between Exchange servers, click the following article number to view the article in the Microsoft Knowledge Base:

Use of the Active Directory directory service and Domain Name System (DNS) for Internet domain names is native to Exchange 2000 Server and Exchange Server 2003. The dot is not supported as part of a domain name or as part of a host name.

For additional information about the consequences of having a dot in the Exchange 5.5 server name in a mixed Exchange environment, click the following article number to view the article in the Microsoft Knowledge Base: