Our organization is cleaning up several years of Outlook archives, and I’ve been assigned to migrate everything into Microsoft 365. We have nearly 200 PST files collected from former employees, backup drives, and old workstations. Some of these files are very large, and they contain business-critical emails, contacts, calendars, and attachments.

I initially planned to follow Microsoft's official Azure Upload method, but after going through the documentation, it feels much more complicated than expected. Between assigning Exchange permissions, uploading files through AzCopy, creating CSV mapping files, and validating import jobs, there seem to be plenty of opportunities for something to go wrong. I’m especially worried about mailbox mapping errors and incomplete imports.

Another concern is maintaining the original folder hierarchy and metadata. We cannot afford missing emails, damaged folders, or duplicate mailbox items because these archives may be needed for audits and legal compliance later.

While researching, I noticed many IT professionals recommend using software to Import PST to Office 365 instead of relying entirely on Microsoft's manual workflow. That approach seems much easier when dealing with multiple users and large PST files.

One application I found was the DRS Softech PST Converter Tool. From what I've read, it supports batch migration, preview before migration, duplicate removal, date filters, and preserves folder hierarchy throughout the migration process. Those features sound useful for reducing manual work while keeping data intact.

Has anyone here migrated hundreds of PST files recently? Did you stick with Microsoft's native import process, or did you use another solution? If you've successfully managed to Upload PST to Office 365, I'd love to know which method proved faster, safer, and more reliable for enterprise-level migrations.