By Rabia Noureen
Publication Date: 2026-11-12 15:30:00
Key Takeaways:
- Microsoft 365 Mailbox Replication Service now supports OAuth authentication for mailbox migrations.
- Organizations can migrate mailboxes without relying on privileged Active Directory usernames and passwords.
- OAuth support is currently available for Microsoft 365 multi-tenant environments and supported Exchange Server deployments.
Organizations migrating mailboxes between on-premises Exchange and Microsoft 365 have traditionally relied on Basic Authentication, which requires storing and transmitting privileged Active Directory usernames and passwords. This approach increases security risks and conflicts with Microsoft’s broader move away from password-based authentication. The Exchange team notes that the Microsoft 365 Mailbox Replication Service (MRS) previously did not support OAuth for these migration scenarios.
Security teams have been forced to maintain legacy authentication…
