How do I implement a migration between two Microsoft Exchange Organizations with the same SMTP name (NETIQKB3493)

How do I implement a migration between two different Microsoft Exchange Organizations with the same SMTP name space?
Do I need to setup forwarders to implement a migration to handle the mail flow when I am using the same SMTP namespace?

Microsoft's recommendation for this configuration involves setting up forwarders on the source and target Exchange servers to handle the mail flow when you are using the same SMTP namespace. Essentially, a forwarder can be set that tells the Exchange server to forward any unresolved mail to a specific Exchange server. Therefore, the Exchange server will search its local directory for the particular e-mail address. If it does not find it, it will forward the e-mail to the specified server.

Please follow the steps outlined below to configure the servers.

1. The initial steps in configuring your environment to share the same SMTP namespace between the Exchange organizations are outlined in the following Microsoft articles.  Both the source and target organizations MUST be configured to handle mail flow between the organizations sharing the SMTP namespace.

   For Source and Target Exchange 5.5 Servers:

   XFOR: How to Configure Exchange to Share SMTP Domain Name Space
   http://support.microsoft.com/default.aspx?scid=kb;en-us;258203

   
   For Source and Target Exchange 2000/2003 Servers:

   How to share an SMTP address space in Exchange 2000 Server or in Exchange Server 2003
   http://support.microsoft.com/kb/321721
   
   For Target Exchange 2007 Server:
   
   How to Configure Exchange 2007 to Route Messages for a Shared Address Space
   http://technet.microsoft.com/en-us/library/bb676395(EXCHG.80).aspx
   
   

2. Confirm mail flow is working properly between the source and target organizations sharing the SMTP name space.

   To ensure mail flow is working between the organizations:

   1. Create a Mailbox in the source organization
   2. Create a Mailbox in the target organization.
   3. Create a custom recipient or contact in the source organization pointing to the target mailbox.
   4. Create a custom recipient or contact in the target organization pointing to the source mailbox.
   5. Verify you can send and receive mail successfully selecting the custom recipient/contact created in steps c and d.
   6. Verify you can send and receive mail to and from external accounts in both organizations.

3. Once your organizations are configured to share the same SMTP namespace, Exchange Migrator MUST be configured with the following script and email address options to ensure the email addresses are set correctly on the target object and source CR created during the migration process.  Configure these migration options before migrating mailboxes.

   Select the following options Within the Specify Migration Options Wizard:

   1. On the Scripting options window, Select 'Yes, I would like to use scripts.'
   2. Select 'I will write VBScripts.'
   3. Click Next.
   4. Select the Event: mailbox-PreProcess.
   5. Enter the following script in the Script field, where @Custom.com is the desired default target SMTP address.
      varsetObject.setProperty "DirMigr.FormatOfTargetMigratedEmailAddress", "@Custom.com."
   6. Click Next.
   7. Select Keep source email addresses (Keep source is optional, all other listed options are required).
   8. Select Translate source addresses to target domain.
   9. Select Use translated Reply-To address.
   10. Select Next.
   11. Complete the migration options wizard. 

Note: The Exchange Migrator User Guide provides a section, Same SMTP Name Space in Source and Target, that outlines an alternate process for migrating between two organizations that share the same SMTP name space.  NetIQ Corporation no longer recommends this proc.
ess because it places an @temp.mydomain.com address on outgoing email from the target organization.  This @temp.mydomain.com address is not transparent to the end user. This KB article outlines the current NetIQ recommended process, therefore the process outlined in the User Guide should not be used unless the process outlined in this KB article cannot be configured in your environment. 

Formerly known as NETIQKB3493