What is PST File Import?
PST (Personal Storage Table) files are Outlook data files that contain emails, calendars, contacts, and other mailbox items. Importing PST files to Microsoft 365 is a common migration method when moving from on-premises Exchange, legacy email systems, or consolidating archived data.
When to Use PST Import
- Migrating from on-premises Exchange Server to Exchange Online
- Importing archived emails from backup PST files
- Consolidating multiple PST files into cloud mailboxes
- Moving data from legacy email systems without native migration tools
- Restoring mailbox data from PST backups
PST Import Methods Comparison
| Method | Best For | Data Size | Speed | Cost |
|---|---|---|---|---|
| Network Upload | Small to medium datasets | < 500GB | Moderate | Free |
| Drive Shipping | Large datasets, slow internet | > 500GB | Fast (once received) | Shipping costs |
| Azure AzCopy | Tech-savvy users, automation | Any size | Fast | Free |
| Third-Party Tools | Complex migrations | Any size | Very fast | $$$ |
Method 1: Network Upload via Microsoft 365 Admin Center
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Network upload is the simplest method for importing PST files. You upload files directly to Azure Storage via your internet connection, then Microsoft imports them into mailboxes.
Prepare PST Files
Organize your PST files and ensure they meet Microsoft's requirements:
- Maximum PST file size: 100GB (recommended < 20GB for faster upload)
- PST files must not be password protected
- Use descriptive file names (e.g., john_doe_archive.pst)
- Store all PST files in a single folder
Create Import Job in Microsoft 365
In Microsoft 365 Compliance Center:
- Go to Data lifecycle management → Import
- Click New import job
- Select Upload your data
- Choose Network upload
- Name your import job (e.g., "Q1 2026 PST Import")
Get Azure Storage URL and SAS Key
Microsoft provides a unique Azure Storage location and SAS (Shared Access Signature) key:
Storage URL: https://3c3e5952a2764023ad14984caa15da12.blob.core.windows.net/ingestiondata
SAS Key: ?sv=2018-03-28&ss=b&srt=sco&sp=rwdlac&se=2024-12-31...
Important: Save these credentials securely. They expire after 14 days.
Install Azure AzCopy Tool
Download and install AzCopy from Microsoft:
# Windows
Download from: https://aka.ms/downloadazcopy-v10-windows
# macOS
brew install azcopy
# Linux
wget https://aka.ms/downloadazcopy-v10-linux
Upload PST Files Using AzCopy
Run AzCopy command to upload your PST files:
azcopy copy "C:\\PST_Files\\*" "https://[storage-url]/ingestiondata?[SAS-key]" --recursive
# Example output:
Job 1234abcd-5678-efgh-9012-ijklmnopqrst has started
Scanning...
Transferring: john_doe.pst (1.2 GB / 5.0 GB) 24%
Elapsed Time (Minutes): 15.3
Create PST Import Mapping File
Create a CSV file that maps PST files to target mailboxes:
Workload,FilePath,Name,Mailbox,IsArchive,TargetRootFolder,ContentCodePage,SPFileContainer,SPManifestContainer,SPSiteUrl
Exchange,john_doe.pst,john_doe.pst,john@company.com,FALSE,/,,,,,
Exchange,jane_smith.pst,jane_smith.pst,jane@company.com,FALSE,/,,,,,
Exchange,archive_2023.pst,archive_2023.pst,admin@company.com,TRUE,/,,,,,
Start Import Job
Back in Microsoft 365 Compliance Center:
- Upload your CSV mapping file
- Review the import settings
- Click Import to Microsoft 365
- Monitor progress in the Import jobs page
Method 2: Drive Shipping (For Large Datasets)
Drive shipping is ideal when you have hundreds of gigabytes or terabytes of PST data and limited internet bandwidth. You copy PST files to encrypted hard drives and ship them to Microsoft's data center.
Drive Shipping Requirements
- 2.5-inch or 3.5-inch SATA II/III internal hard drives
- Drives must be encrypted with BitLocker (Windows) or compatible encryption
- Maximum 10 drives per shipment
- Ship to Microsoft's designated data center (location provided in portal)
Create Drive Shipping Job
In Microsoft 365 Compliance Center, create a new import job and select Ship hard drives. Microsoft will provide shipping address and journal file.
Prepare Hard Drives
Use WAImportExport tool to copy PST files and encrypt drives:
WAImportExport.exe PrepImport /j:journal1.jrn /id:session1 /srcdir:C:\\PST_Files /dstdir:PST /encrypt /logdir:C:\\Logs
Ship Drives to Microsoft
Package drives securely and ship to the address provided by Microsoft. Include the journal file and tracking information in the portal.
Microsoft Processes Import
Once Microsoft receives your drives, they upload the PST files to Azure Storage and import them to mailboxes. You'll receive email notifications about progress.
Method 3: Using Third-Party Migration Tools
Third-party tools offer advanced features like automated PST discovery, parallel uploads, and detailed reporting. Popular options include:
BitTitan MigrationWiz
Automated PST import with user-friendly interface and excellent support.
- • Automatic PST discovery
- • Parallel uploads
- • Detailed migration reports
- • $12-$15 per mailbox
Quest On Demand Migration
Enterprise-grade solution with advanced filtering and scheduling.
- • Advanced content filtering
- • Scheduled migrations
- • Compliance features
- • Custom enterprise pricing
SkyKick Migration Suite
MSP-focused tool with automated PST handling and backup features.
- • Automated PST consolidation
- • Built-in backup
- • White-label options
- • $10-$20 per mailbox
Kernel Import PST
Budget-friendly option for smaller migrations with basic features.
- • Simple interface
- • Batch PST import
- • Affordable pricing
- • $199-$499 one-time
PST Import Best Practices
Optimization Tips
Before Import
- Split large PST files into smaller chunks (< 20GB)
- Remove password protection from PST files
- Run PST repair tool (scanpst.exe) on corrupted files
- Delete unnecessary emails to reduce size
- Use descriptive file names for easy mapping
During Import
- Upload during off-peak hours for faster speeds
- Monitor upload progress regularly
- Keep source PST files until import is verified
- Test with a small batch before full import
- Document any errors for troubleshooting
Common PST Import Issues
PST File Corruption
Problem: Import fails due to corrupted PST files.
Solution: Run Microsoft's Inbox Repair Tool (scanpst.exe) to fix corruption. If repair fails, use third-party PST recovery tools or restore from backup.
Slow Upload Speeds
Problem: PST upload taking much longer than expected.
Solution: Use AzCopy with parallel upload options, upload during off-peak hours, check network bandwidth, consider drive shipping for very large datasets.
Mailbox Size Limits
Problem: Import fails because target mailbox is full.
Solution: Enable archive mailbox, increase mailbox quota, or import to archive mailbox instead of primary mailbox.
Mapping File Errors
Problem: CSV mapping file has formatting errors or incorrect paths.
Solution: Verify CSV format matches Microsoft's template exactly, check for special characters, ensure file paths match uploaded PST names, validate email addresses exist.
Post-Import Verification
Verification Checklist
Check Item Counts
Compare number of items in PST vs imported mailbox
Verify Folder Structure
Ensure all folders imported correctly with proper hierarchy
Test Email Functionality
Open emails, check attachments, verify dates preserved
Review Import Logs
Check for any errors or warnings in import job logs
User Acceptance Testing
Have users verify their data imported correctly
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