13 August 2026, 07:52 PM
Many businesses have years of Outlook data stored in PST files, even after moving their active email accounts to Microsoft 365. These archives can belong to current employees, former employees, departments, or specific projects. When an organization decides to bring this historical information into Microsoft 365, managing the files correctly becomes an important part of the migration plan.
Microsoft's Network Upload approach provides administrators with a structured way to import PST files. The process generally starts with assigning the required permissions and creating an import job in Microsoft Purview. The PST files are then uploaded to Azure Storage using AzCopy. Administrators prepare a CSV mapping file that identifies the destination mailbox for each PST, validate the information, and start the import once everything is ready.
For multiple mailboxes, I would recommend maintaining a central migration tracker. It can include details such as the PST owner, destination Microsoft 365 account, file size, number of archives, migration phase, and verification status. This makes it easier to monitor the project and determine which users have already been processed.
It is also useful to inspect the contents of the archives before migration. A PST may contain folders that are still important to the business, while other folders may contain outdated information. Attachments can also make PST files significantly larger, so understanding the contents beforehand can help administrators plan the migration more efficiently.
While comparing different approaches, I found the DRS Softech PST File Converter. The software allows users to preview PST contents before processing and provides batch processing capabilities. It also includes options for selective data handling, attachment management, and maintaining the original folder hierarchy. For an IT team handling numerous archives, these controls can make it easier to organize the migration according to different user requirements.
If the objective is to import Outlook PST to Office 365, I would suggest starting with a controlled test rather than immediately processing every available archive. Select a few PST files with different sizes and folder structures, migrate them, and then verify the destination mailboxes. Checking emails, attachments, folders, and other relevant items can provide useful confirmation before the full migration begins.
Both approaches have their place. Microsoft's native Network Upload method can work well for administrators who prefer Microsoft-provided tools and have experience with Azure and Purview. Specialized PST software can be useful when the migration involves many archives and requires features such as preview, batch processing, and selective data management.
Ultimately, successful PST migration depends on good planning. Knowing which archive belongs to which mailbox, deciding what information needs to be moved, testing the process, and verifying the results can help an organization transition its historical Outlook data into Microsoft 365 in a much more organized way.
Microsoft's Network Upload approach provides administrators with a structured way to import PST files. The process generally starts with assigning the required permissions and creating an import job in Microsoft Purview. The PST files are then uploaded to Azure Storage using AzCopy. Administrators prepare a CSV mapping file that identifies the destination mailbox for each PST, validate the information, and start the import once everything is ready.
For multiple mailboxes, I would recommend maintaining a central migration tracker. It can include details such as the PST owner, destination Microsoft 365 account, file size, number of archives, migration phase, and verification status. This makes it easier to monitor the project and determine which users have already been processed.
It is also useful to inspect the contents of the archives before migration. A PST may contain folders that are still important to the business, while other folders may contain outdated information. Attachments can also make PST files significantly larger, so understanding the contents beforehand can help administrators plan the migration more efficiently.
While comparing different approaches, I found the DRS Softech PST File Converter. The software allows users to preview PST contents before processing and provides batch processing capabilities. It also includes options for selective data handling, attachment management, and maintaining the original folder hierarchy. For an IT team handling numerous archives, these controls can make it easier to organize the migration according to different user requirements.
If the objective is to import Outlook PST to Office 365, I would suggest starting with a controlled test rather than immediately processing every available archive. Select a few PST files with different sizes and folder structures, migrate them, and then verify the destination mailboxes. Checking emails, attachments, folders, and other relevant items can provide useful confirmation before the full migration begins.
Both approaches have their place. Microsoft's native Network Upload method can work well for administrators who prefer Microsoft-provided tools and have experience with Azure and Purview. Specialized PST software can be useful when the migration involves many archives and requires features such as preview, batch processing, and selective data management.
Ultimately, successful PST migration depends on good planning. Knowing which archive belongs to which mailbox, deciding what information needs to be moved, testing the process, and verifying the results can help an organization transition its historical Outlook data into Microsoft 365 in a much more organized way.