Enabling search for Microsoft Exchange migrated mailboxes

With every mailbox migration from Microsoft Exchange On-premises to Microsoft Exchange Online or the other way around, the mailbox Distinguished Name (DN) changes. Content Collector uses the mailbox DN to identify mails that belong to a particular mailbox. Due to such migration scenario, the mails processed by Content Collector that belong to the same mailbox can have multiple mailbox DNs in the repository. To handle this scenario, you can create a mapping that links all the mailbox DNs so that the Content Collector functionality work as expected.

1. Copy the ExchangeHybrid folder, which has the PowerShell scripts from the following location and paste it in a temporary directory on the Exchange server:
   <ICC_installation_path>\tools\ExchangeHybrid
2. Open PowerShell with administrator privileges.
3. Run the following PowerShell script to fetch the migrated mailbox IDs associated with Exchange Online users:
   Get-ExchangeOnlineUserMailboxDNs.ps1

   Examples:

   • Get-ExchangeOnlineUserMailboxDNs.ps1 <username>@<domain>.com
   • Get-ExchangeOnlineUserMailboxDNs.ps1 <user1>@<domain>.com , <user2>@<domain>.com , ..
   • Get-ExchangeOnlineUserMailboxDNs.ps1 *@<domain>.com
4. Sign-in with administrator credentials when prompted.
   After successful execution of the script, a file is generated: ExchangeOnlineUserMailboxDNs.csv.
5. Open the Microsoft Exchange On-premises Management Console.
6. Run the following PowerShell script to fetch the migrated mailbox IDs associated with Exchange On-premises users:
   Get-ExchangeOnpremiseUserMailboxDNs.ps1

   Examples:

   • Get-ExchangeOnpremiseUserMailboxDNs.ps1 <username>@<domain>.com
   • Get-ExchangeOnpremiseUserMailboxDNs.ps1 <user1>@<domain>.com , <user2>@<domain>.com , ..
   • Get-ExchangeOnpremiseUserMailboxDNs.ps1 *@<domain>.com

   After successful execution of the script, a file is generated: ExchangeOnpremiseUserMailboxDNs.csv.

7. Run the following PowerShell script to merge the CSV files generated in steps 4 and 6:
   Merge-UserMailboxDNs.ps1

   Example: Merge-UserMailboxDNs.ps1 'ExchangeOnlineUserMailboxDNs.csv', 'ExchangeOnpremiseUserMailboxDNs.csv'

   After successful execution of the script, a file is generated: ExchangeOnlineMigratedUsers.csv.

   Note: The purpose of the merge script is to merge the output of Exchange On-premises and Exchange Online mailboxes in the form of two different .csv files. If you do not have one of the two CSV files, rename the one you have to ExchangeOnlineMigratedUsers.csv and proceed with the next step.
8. Copy the file that is generated in step 7 and paste it in the following location on the Content Collector server:
   <ICC_installation_path>\MigratedUsersCSVFile