Migrate Outlook PST to Shared Mailboxes in Microsoft 365: 2026 Guide for Enterprise Users

Why Import PST File to Shared Mailboxes?

There might be different reasons why M365 administrators or system administrators migrate their Outlook data file to a shared mailbox. A few of them are listed below. 

• Centralise legacy PST data into a single Microsoft 365 mailbox.
• Provide permissioned access for appropriate team members to shared business communications.
• Archive crucial email and records upon departure.
• Minimise reliance on a local PST file to archive historical communications.
• Archive company, project, sales, marketing, and support correspondence.

Common PST to Shared Mailbox Migration Scenarios

• Employee offboarding requires historical emails to remain accessible.
• Departments need to consolidate multiple PST archives in one mailbox.
• Support teams need to centrally access the historical customer conversations.
• Organisations need to move locally stored PST data into Microsoft 365.
• Also, IT administrators need to map multiple PST files to a shared mailbox.

Considering the above scenarios, the need to perform some preliminary steps before you migrate PST files to shared mailboxes is essential.

Prerequisites: Before You Migrate Outlook PST to Shared Mailboxes

Follow the checklist below to achieve an accurate migration without any data loss or discrepancies. 

1. Create your target shared mailbox within the Microsoft 365 Admin Center.
2. Grant ‘Send As‘ and ‘Full Access‘ permissions to the right individuals.
3. Discover and confirm all the source PST files on different systems.
4. Check the source PST files for any corruption prior to migration.
5. Verify that the shared mailbox does not reach its storage quota limits.
6. The internet connection must remain available throughout the process.
7. Back up original PST files before migration begins.
8. Also, keep the end-users notified about the PST migration plan in advance. 
9. Begin by testing the migration with a single PST file.

Manual Method to Migrate Outlook PST to Shared Mailboxes

Microsoft’s native import service, driven through PowerShell and the Security & Compliance Center, lets admins upload PST files to Azure and target a Shared Mailbox directly. It suits organisations with few PST files and technical admin resources.

Steps to Move Complete Outlook Mail Data into Office 365 Shared Mailboxes

1. Sign in to the Microsoft Purview compliance portal.
2. After that, navigate to Data Lifecycle Management > Import.
3. Generate a SAS URL via Azure AzCopy and upload all PST files to Azure Storage.
4. Build a mapping CSV linking PST files to the Shared Mailbox and submit it to start the import job.
5. Apply date range filters and choose a target folder if only partial data is needed.
6. Track job status from the compliance portal dashboard and resolve any reported errors.
7. Confirm mail, folders, and attachments transferred correctly, then notify users the shared mailbox is ready.

Enterprise Solution to Migrate Outlook PST to Shared Mailboxes

The Aryson PST Outlook Converter is a Graph API-based utility that helps organisations migrate 1,000+ PST files to shared mailboxes simultaneously. Moreover, it ensures 100% data retention and preservation of data during the migration. The batch processing feature and CSV import functionality make it stand out. Along with that, the advanced features of the software, like date range filtering and skipping previously migrated files, allow firms to migrate the filtered data without investing hours in this process.

Important: Not just Shared Mailbox users can also migrate PST files to Google Workspace within a few clicks. 

Step-By-Step Guide to Transfer Outlook emails into shared mailboxes

1. Download and run the Aryson PST Converter tool for Windows/Mac operating systems.
2. Then, add the PST files via the file selectors or the drag-and-drop functionality. 
3. Cross-verify the loaded file items and select the relevant ones to migrate. 
4. Under the Email Clients dropdown list, select Office 365 as the destination. 
5. Log in to the Office 365 account via the Modern OAuth or impersonation method. 
6. You can even use the required filters as per your requirements >> Start Migration. 
7. At last, monitor the progress via the monitoring dashboard. 

Enterprise-Grade Features of This Utility

• Migrates emails, contacts, calendars, and attachments together.
• Bulk-imports multiple PST files using folder scan.
• Includes date range filter for selective migration.
• Skips duplicate items to avoid redundant data.
• Preserves original folder hierarchy and metadata.
• Supports Modern Authentication and Admin (DWD) login.
• Provides real-time tracking with detailed reports.
• Offers a free demo migrating 50 items per folder.

Conclusion

Enterprises and system administrators migrate Outlook PST to Shared Mailboxes to keep their business data secure and centralised for the associated teams and departments. For this, they might use the manual method or use the Aryson PST to Office 365 tool. Since each method serves different purposes, it is essential to opt for the migration method as per your requirements. To manage large PST volumes, it is recommended to proceed with the professional software, as it provides a CSV import feature specifically for this purpose. Moreover, live chat support is available 24/7 for personalised assistance for the end-user. 

Frequently Asked Questions

About The Author:

Harshita Sachdeva

Harshita Sachdeva, a professional technical writer at Aryson Technologies, specialize in delivering clear, hands-on documentation for data management, migration, and recovery solutions. With a meticulous, reader-first approach, I break down complex technical processes into simple, actionable content - helping IT professionals and decision-makers tackle challenges efficiently.