Sometimes in Exchange Online migration projects you have the demand to make not few big batches but many small ones. In the end this means you have many CSV files which you want to use for bulk creation of migration batches.

You can either create them by using the GUI (which is not really fun when you have more than 10 CSV files) or by using this tiny PowerShell command. You have to replace the highlighted values with your own ones:

Get-ChildItem *.csv  | Foreach-Object{ New-MigrationBatch -Name ($_.Name -replace ".csv","") -TargetDeliveryDomain "TENANTNAME.mail.onmicrosoft.com" -AutoStart -AllowUnknownColumnsInCsv $true -NotificationEmails "YOUR.EMAIL@DOMAIN.COM" -CSVData ([System.IO.File]::ReadAllBytes( $_.FullName)) -BadItemLimit 99999 -LargeItemLimit 99999 -AllowIncrementalSyncs $true -SourceEndpoint "NAME OF YOUR HYBRID ENDPOINT"}

 

This command searches for all CSV files in the current folder and creates a migration batch for each CSV file with the following attributes:

  • The name of the batch will be the file name of the CSV file without the file extension
  • The batch will start automatically but has to be completed manually
  • The notification emails will be sent to the email you provide here
  • The CSV files may have any column, but the column “EmailAddress” must be present
  • The batches will perform incremental syncs
  • the LargeItemLimit and BadItemLimit are very high to ensure the mailboxes will not skip because of items that can’t be migrated
  • The hybrid endpoint of your organization will be taken for the move

Of course you may adjust this command depending on your needs, e.g. Auto Completion or a lower BadItemLimit.

In my case there was a limit of 100 migration batches. The Exchange Online Service Description doesn’t mention this limit, but be aware of the fact that this may hit you as well.

Happy migrating 🙂

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