Step by step – Microsoft Import Service Office 365 (PST Files)

Let’s discuss Microsoft Import Service Office 365! Last time, we went through E-Mail migration using a third party tool: Dell On-Demand Migration. Check that instead if Microsoft Import Service is not sufficient for your needs.

In some scenarios though, you’re better fit using the Import service Office 365. This is a great tool delivered last year by Microsoft. This step by step guide is intended to help you upload your PSTs to Office 365 and import them to your user-mailboxes. Let’s start!

Step by step Microsoft Import Service Office 365

This guide is intended for small companies, as uploading several terabytes of PSTs might not be your cup of tea. That said, Microsoft also lets you ship physical drives with data to them, where they will import it for you! Obviously they will not combine them with the usermailboxes, but after the initial upload, you’re halfway there.

Also, if you’re in need of incremental sync, as the Dell On-Demand Migration provides, stop reading now and jump on that guide instead.

PST files, or Personal Storage Table file, is a file format used to store copies of messages, calendar events and other items within Microsoft software.

You can find PSTs on the PC running Outlook, or for all users on the current Exchange server.

Note: This guide is intended for mass exporting and importing PST files, which means we will be looking at Exchange servers.


  • Exchange Online/2016/2013/2010: To Export PST files from Exchange. You need the “Mailbox Import Export” Role. Add this with Powershell by typing the following on the Exchange server:
New-ManagementRoleAssignment -Role "Mailbox Import Export" -User "user name or alias"

Note: Do this on both the exporting end (your current server), and the receiving end (Exchange Online tenant). The import to mailboxes will fail if you do not have this role in Exchange Online.

  • On the Exchange server, grab all your relevant PST files either by bulk (CSV file or search), and type in the following:
    New-MailboxExportRequest -Mailbox "usermailbox" -FilePath "\\SERVER01\PSTFileShare\usermailbox.pst"

    There are many available parameters. If needed, be sure to check them out to further configure New-MailboxExportRequest.

Exporting to Office 365 – Azure Storage

The Import Service Office 365 isn’t too hard, but we still have to follow some steps, and make sure they are correct all the way.

Now that you’ve got all your PSTs ready and willing, we have to upload them somewhere. For this we will use Azure, from the Microsoft Import Service.

Head to Office 365 Portal-Ingestion site by clicking this link, or follow step by step:

  • Click on Users ⇒ Data Migration


  • As shown above, click on Upload PST files
  • This will lead you to the ingestion site. Click on and Upload email messages (PST files):



  • Here we will copy our unique SAS URL – the whole URL. Click on “Show SAS Network Upload SAS URL”:

  • After copying the key, download and install the tool from step 3 in the picture above. Direct link to Azcopy-tool
  • Open CMD
  • The correct syntax would be something like this :
AzCopy.exe /Source:\\FILESERVER1\PSTs /Dest:"" /V:C:\Users\Admin\Desktop\AzCopy1.log

Note: Make sure your Source is the correct folder where your PSTs are uploaded. For simplicity sake, I choose to upload them directly to my SAS URL, without adding any subfolders. If you’d like, you can add “/PST” or something to your SAS URL to create a new folder in Azure for your PSTs. Official Microsoft documentation on Azcopy-CMD here

  • Go to where you chose to Install Azure Storage Tools (Default: C:\Program Files (x86)\Microsoft SDKs\Azure\Azcopy) and hold in Shift while you right click. Click on Open command window here:


  • Type in your custom syntax for running azcopy PST uploading, and watch the uploading begin. Make sure to check the log if something fails:Import Service Office 365

(Optional) Viewing your PSTs in Azure Storage Explorer

Before we continue, if you’re uncomfortable assuming that your PST files are in fact in Azure Storage, you can download and install Azure Storage Explorer.

Open Azure Storage Explorer and choose “Connect using your Storage Account information” and click Next:


Use the SAS URI you saved and used in azcopy at the next screen:


Click Next and Connect, now you’ll be able to see all your uploaded PSTs in Storage Accounts ⇒ (SAS-Attached Services) ⇒ Blob Containers ⇒ ingestiondata :


Importing PSTs to the correct mailboxes

Now that we’ve uploaded all our PSTs, we can move on to the next step! Mapping the users to their respective PST-files.

  • Download the example mapping CSV-file from Microsoft here
  • Open the example CSV-file in Excel to edit it:importservice9


Filepath: This needs to be set to where you uploaded it. Leave it blank if you uploaded directly to the SAS URI. If you appended something like you will use PSTFiles instead, or else the Import Service won’t find the PSTs

Name: Refers to the PST-file uploaded.

Mailbox: Refers to the target destination in Exchange Online. Which mailbox will receive the correctly named PST-file.

IsArchive: Defines if this is an archive PST or not

TargetRootFolder: This defines where you import the messages in the users mailbox. Choose “/” if you’d like them to be imported to the root folder. If you leave it blank, the messages will appear in a folder named “Imported”. Define a name if you’d like the folder to be something more specific.

  • With the CSV file ready, let us mark all the checkpoints on our Import-tab, and click next:


  • Create a name for the migration, and click next:


  • Click on to add the CSV Mapping file. If it’s under 100 rows, you have to Validate the file first. Check for errors if there are any, check the box to agree to whatever the terms are and click next!


That’s it. The import-service will start shortly and start working its magic!

Next steps

You can check the progress on the Ingestion-site at any time during the migration:


Clicking on View Details will help you take a closer look per mailbox. If there are any problems, you will see them there:Import Service for Office 365

When “Items imported” start showing something else than 0, you can verify on the users mailbox that the items are in fact present.

That’s it, you’re done. Hopefully this has shown how to use the Microsoft Import Service Office 365!

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