What is the Office 365 PST Import Service?
The Import service in the Microsoft Purview portal bulk imports PST files into Exchange Online mailboxes. You send the files to a temporary Azure Storage location. The service then imports the data.
Microsoft lists two methods on its PST import overview page. The network upload method is the main path for the mapping file steps below.
| Method | Cost | Limits | Use case |
|---|---|---|---|
| Network upload | Free | Several hours per TB | Ongoing or smaller moves |
| Drive shipping | Costs apply | 10 TB per drive and 10 drives per batch | Large one time moves |
What do You Prepare Before the PST Import?
Microsoft lists the permissions and limits on the overview page. Check them before the network upload.
- Assign the Mailbox Import Export role in Exchange Online. No role group holds it by default. Add it to Organization Management or a new role group.
- Assign the Mail Recipients role. Organization Management and Recipient Management have it by default.
- Use PST files at or below 20 GB. Larger files can slow the import.
- Expect that items above 150 MB are ignored.
- Expect that a PST file with 300 or more nested folder levels fails.
- Use Unicode PST files from Outlook 2007 or later when you can.
- Prepare the mapping file with one row for every PST file.
Heads Up. A global administrator account passes the permission check without the two roles.
How does the AzCopy Network Upload Work?
Method #1: Network Upload With AzCopy (Free)
Who it suits. Admins who import many PST files into Exchange Online. Extra application. AzCopy from the Import page.
- Sign in to the Microsoft Purview portal.
- Go to Data lifecycle management, then Microsoft 365 and then Import.
- Select New import job and enter a name. Use lowercase letters, numbers, hyphens and underscores only.
- Select Upload your data and then Next.
- Select Show network upload SAS URL, copy it and save it in a safe place.
- Select Download Azure AzCopy.
The SAS URL is unique to your organization. Protect it like a password. The network upload sends the files to Azure Storage.
Open a command prompt in the AzCopy folder and start the upload.
azcopy.exe copy "<Source location of PST files>" "<SAS URL>"The source is a folder, for example a file share. You cannot name a single file.
Add a subfolder name after ingestiondata in the SAS URL when you want the files in a subfolder. Match every folder name in the mapping file to the subfolder in the SAS URL.
Use only the AzCopy version from the Import page for the network upload. Microsoft does not support other versions.
How do You Build the Mapping File?
The mapping file is a CSV file that links every PST file to a mailbox. Microsoft states a limit of 500 rows per file, so use more files and more import batches for a larger move.
Use the header row exactly as Microsoft gives it. The main columns are below.
| Column | Value |
|---|---|
| Workload | Exchange |
| FilePath | The subfolder name from the SAS URL. Enter nothing without a subfolder. |
| Name | The PST file name. The value is case sensitive and unique in the batch. |
| Mailbox | The user email address. Use the ExchangeGuid for an inactive mailbox. |
| IsArchive | FALSE for the primary mailbox and TRUE for the archive mailbox |
| TargetRootFolder | Blank creates an Imported folder. A slash merges into the top level. |
Upload the mapping file in the import steps below. A PST name or FilePath that does not match the uploaded file exactly makes that import fail. Archive imports go to the main archive and stop at 100 GB per import.
How do You Start the Import?
- Go to Import and select New import job again.
- Select Upload your data and then Next.
- Select I'm done uploading my files and I have access to the mapping file.
- Select the mapping file and select Validate. Open View log when validation fails.
- Accept the terms and select Save.
- Select Refresh until the status shows Analysis completed.
- Select the entry and then Import to Microsoft 365.
- Choose to filter by item age and message type or select the option to import everything. Select Import data.
Monitor the status on the Import PST files page. The status shows Complete at the end.
Microsoft states that the service deletes the uploaded files 30 days after the latest import batch when no import is in progress.
The service sets retention hold on the mailbox after the import. Retention policies remain paused until you disable it.
When does Drive Shipping Fit?
Method #2: Drive Shipping (Paid)
Who it suits. Companies with huge one time archives. Extra application. BitLocker drives.
You copy the PST files to a BitLocker encrypted drive and ship it to Microsoft. A drive holds up to 10 TB and a batch takes up to 10 drives.
Microsoft uploads the data 7 to 10 business days after it receives the drive. The method needs a Microsoft Enterprise Agreement and is not available in Germany or Switzerland.
How do You Import One PST File Without the Service?
Method #3: Outlook Import Wizard (Free, One Mailbox)
Who it suits. Users who import into their own mailbox. Extra application. None.
- Open Outlook and select File, then Open & Export and then Import/Export.
- Select Import from another program or file and then Outlook Data File (.pst).
- Choose the file and the duplicate handling option.
- Select the destination folder and select Finish.
Microsoft lists the steps on its page for importing a PST file into Outlook. Read the guide to import a PST file in Outlook for more detail.
What Fixes Common PST Import Errors?
- Validation fails. Open View log and match every PST name and FilePath in the mapping file to the uploaded files.
- The next attach in Azure Storage Explorer fails. Detach the container when you finish. Storage Explorer cannot upload or edit files.
- A PST file is too large. Divide it with the guide to split a large PST file.
- A mail item is missing. Check whether the item is above 150 MB.
Where Else do You Go From Here?
- Read the guide to import PST files to Office 365 for the full list of options.
- Create a backup after the import with the guide to backup Office 365 to PST.
Frequently Asked Questions
Is the PST Network Upload Method Free?
Yes. Microsoft states that network upload is free.
What Role do You Need for the PST Import Service?
Assign Mailbox Import Export and Mail Recipients. A global administrator account works too.
What Size should a PST File have for the Import Service?
Microsoft asks for PST files of 20 GB or less.
Can AzCopy Upload a Single PST File?
No. The source must be a folder or an Azure Storage location, not a single file.
How Many Rows Fit in the Mapping File?
Microsoft states a limit of 500 rows per mapping file.
What Happens to the Uploaded PST Files After the Import?
The service deletes them 30 days after the latest import batch when no import is in progress.
Does the Import Service Ignore Large Mail Items?
Yes. The service ignores items above 150 MB because of the Exchange Online size limit.
Author's Verdict
Use network upload for many PST files and a clean mapping file. Use the Outlook wizard when a network upload is too much for one mailbox.
Limit every PST file to 20 GB and match every name in the CSV file exactly.
Key Takeaways
- Network upload is free and needs AzCopy from the Import page.
- The mapping file links every PST file to a mailbox.
- The service pauses retention policies on the mailbox after the import.
Related Guides
Want the upload command alone? Read how to import PST files to Office 365 with AzCopy.