Our company recently migrated to Microsoft 365, and I was given the task of organizing several years of archived emails stored as MSG files. The archive contains more than 10,000 messages spread across dozens of folders, and management wants everything available in one cloud mailbox for easy access and compliance purposes.

I first tried manual methods to Import MSG to Office 365, including drag-and-drop and copy-paste. While those approaches worked for a small number of emails, they became extremely slow when handling larger batches. Outlook would occasionally freeze, and I noticed that some folder structures were not preserved correctly. Reorganizing everything manually would have taken days.

Another challenge was ensuring that users could easily open MSG file in Office 365 after the migration. Many of these emails contain attachments, project documents, invoices, and important client communications, so preserving metadata and formatting was critical.

After testing different options, I used the DRS Softech MSG Converter Tool. The software allowed bulk migration directly to Office 365 and maintained email properties such as sender information, dates, attachments, and folder hierarchy. The filtering options were also useful because I could exclude unnecessary emails before starting the import.

The migration completed successfully, and now the entire archive is searchable within Outlook 365 across desktop, web, and mobile devices. For those who have handled large MSG archives, what methods or tools worked best for you? I'd love to hear other recommendations and experiences.