A Step-by Step Guide to a PST Free Environment

Limited mailbox size due to limited mailbox database size due to on-premises server’s disk space due to the number of users. Sound familiar?
On-premises Exchange servers always dictates the server disk space and that always comes down to proper user profiling and limiting the per user mailbox capacities.

Result of this? Archive the emails in to PST Files and store it in a file server or in the user’s computers it self. How risky this process is that it can lead to deletion of the file with no backups of it if its in the user’s computer or corrupted file or too many PST files that the user can’t keep a track of and they can be sitting everywhere. Basically this is a nightmare.

Sick Work GIF


The feature I’m illustrating here is not a new tool, but with the trend of organizations moving to the cloud and Exchange Online in particular, chances are they might miss the smaller points like moving the existing PST files on to the cloud mailbox.

Import to Mailbox or Online Archive?

You can always migrate the content in the PST file in to the user’s current Exchange Online mailbox. However this can be a temporary solution as the size of the archived PST file may close to user’s mailbox size and this can easily make the mailbox go full.

Enabling Online Archiving can be a long term solution as every mailbox user (except F3) has got the Online Archive space as a part of their license

Exchange Online and Online Archiving mailbox sizes

If you check the Exchange Online Service description, you can see the below limitations according to the plan you are in. F3 doesn’t come with any Online Archiving solution, however you can purchase the Online Archive Add-on separately
Article: Exchange Online Limits

How to enable Online Archiving?

There are few mix and match options you can go by. I would like to focus on the scenario where the user mailboxes are in the cloud and licensed properly so you can enable the Online Archiving feature

Options for Hybrid (where you enable In-place archiving that will enable on cloud OR Straight from on cloud for the user who has their regular mailbox on-prem but the archive in cloud)

Before you enabling Archiving – Make sure you have the Retention Policies setup and the users are aware where to look if the items in the current mailbox starts archiving automatically depending on the retention policy you have setup

It’s good to keep in mind that Online Archving is not caching the headers of the items as the normal mailbox does in the cached mode. Meaning, to browse the Online Archive, you need to be online.

Few Places to look for options (of course there are few places always)

  • Option 1 – Enable from the ECP (Exchange Control Panel) > Search for the remote user > From the right-hand panel select Enable for the In-Place Archiving
    This will activate the Online Archive after the next sync

— This will take few minutes to enable and will appear in user’s Outlook/ OWA just under the standard mailbox

Go straight with Option 2 if you don’t have a Hybrid Setup.

Move PST file to Online Archive

Few gotchas!

  • To import PSTs to the mailbox – You must be assigned the Mailbox Import Export role in Exchange Online > Permissions. After this role is assigned, it might take up to 24 hours before you can start creating jobs
  • To create import jobs in the Security & Compliance Center, one of the following must be true: You have to be assigned the Mail Recipients role in Exchange Online. By default, this role is assigned to the Organization Management and Recipient Management roles groups. Or
    You have to be a global administrator in your organization
  • The only supported method of uploading PST files to Microsoft 365 at the moment is the AzCopy tool and Storage Explorer tool won’t be able to perform the upload
  • By default a Microsoft 365 mailbox send/ receive sizes are capped at 35MBs. However the maximum you can go is 150MBs. If you have items in the mailbox that are larger than 35MBs, best to increase the receive limit on the mailbox prior import
  • Make sure you name the archive PST files properly or it’ll be hard to find who own the file (eg: username-archive1.pst, username-archive2.pst)

The process

  1. Upload the PST files sitting in on-premises to the Azure Blob storage using the AzCopy tool
  2. Send the uploaded archive files to the respective user mailboxes/ Online Archives using the mapping file

Task 1: Upload the PST files using the AzCopy tool

  • Download the AzCopy tool from this URL as other AzCopy tools may not work according to Microsoft.
  • Go to https://protection.office.com and sign-in with the admin account as mentioned previously
  • Go to Information governance > Import > Import PST files
  • Click on New Job and name the Import Job
  • Make sure you click on Upload your Data for the question “Do you want to upload or ship your data?
  • Once you press Next, you’ll get the below screen

I will walk you through the steps as we will not complete this step yet but just grabbing some information.

  • Click on “Show network upload SAS URL” and it will provide the URL
    Copy the URL
  • Next step will be to download the AzCopy tool, but as we have already done that part, I will skip this part.

We can leave the Compliance andSecurity portal for a while now as we have to upload the PST files

Upload PST files

  • Preparing the upload command is the next step
    The PowerShell command is as below

The full set of parameters can be found here

AzCopy.exe /Source: /Dest: /V: /Y

Eg: AzCopy /Source:”\FS01\PSTs” /Dest:”https://3c3e5952a2764023ad14984.blob.core.windows.net/ingestiondata?sv=2012-02-12&se=9999-12-31T23%3A59%3A59Z&sr=c&si=IngestionSasForAzCopy201601121920498117&sig=Vt5S4hVzlzMcBkuH8bH711atBffdrOS72TlV1mNdORg%3D” /V:”c:\Users\Admin\Desktop\Uploadlog.log” /Y

  • This will now start uploading the files to the Storage Blob and once it’s done, it will give the below result.

Install the Storage Explorer

This is an optional step but installing the Storage Explorer and connecting with the SAS Key to get a better view on the uploaded file. This is in read-only mode

Download link can be found here: https://azure.microsoft.com/en-us/features/storage-explorer/

  • Connect to the Storage Blob by using the SAS URL
    Select “Use a shared access signature (SAS) URI” option
  • Enter the SAS URI as below and press the Connect button in the next screen
  • Storage Explorer will show the details as below. The data in the Storage Blob will be deleted automatically after 60 days.

This ends the uploading and verifying task

Task 2: Send the uploaded PST files to the mailboxes by using the mapping file

Lets get back to where we left off in the Compliance and Security portal. That the Step 4 of the Import task
I’ve created the below example only with the necessary data

Explaining what’s in the mapping CSV file
This has 2 archive files (shehan-archive1.pst and shehan-archive2.pst) going into the user’s mailbox but in to the main folder called ARCHIVE

The PST file called analyzer.pst is migrating to the Online Archive portion of the user’s mailbox because the IsArchive is set to TRUE and you can see the TargetRootFolder path as well

Need to make sure the Online Archive is enabled for the user before the migration starts

The final step is to go back to the Import Data page in Compliance and Security page and complete the task

  • Check both I’m done uploading my file and I have access to the mapping file options and press Next
  • Upload the Mapping file (the CSV file we prepared) and press Validate
  • Press Save once the validation is done
  • Press Close
  • This will start the analysis process in the jobs list
  • The next state will be the batch is ready to upload message
  • Click on Ready to import to Office 365 and it will give you the screen to select the date range to upload
  • Click on Import to Office 365
  • Depending on the filter option, you have the option upload emails from a range or all
  • And click on Import Data button in the next screen and will show the summary of the file/s in the import job
  • The admin who initiated the import job will also receive an email regarding the status
  • And the email when the job has been completed
    The admin can always check the status of the import job as mentioned below for any errors and warnings.

It’s time to let Microsoft do it’s work. The upload task will take some time depending on the PST file capacities

Check if the PST file has been moved?

Once the import job has completed, open Outlook or OWA and you will see the folder structure has been created in the specified path in the mapping file’s TargetRootFolder. The same folder structure in the PST fie will be created in the upload location so the user will see no difference


The goal is to import the on-premises PST files in to Microsoft 365 and get rid of that dependency. You can further set retention tags to Online Archiving and also the retention policies can be setup according to the users (individual or batch of users) because the default MRM Policy may not work for all the industries.
Hope this will helpful you to decide and guide to upload the PST files and tick that box off.

Feature Image: Vector image by VectorStock / VikaSuh


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