We are happy to announce that Microsoft 365 Mailbox Replication Service (MRS) now supports OAuth as an authentication method when migrating mailboxes between Microsoft 365 and an on-premises Exchange environment. OAuth offers a secure alternative to using the Basic authentication credentials (username and password) of a privileged on-premises Active Directory user.
Until now, MRS has not allowed customers to authenticate with OAuth for these migrations. Once OAuth for MRS is configured, tenant administrators can create an OAuth migration endpoint and use it in migration batches or in onboarding and offboarding move jobs. You can use this method in both hybrid and non-hybrid organizations.
OAuth for mailbox migration is available:
- In Microsoft 365 multi-tenant (WW) environments only. We will have news about availability in other cloud environments over next several months.
- For on-premises organizations running the October 2026 or newer version of Exchange Server Subscription Edition (SE) or Exchange Server 2019 CU15 with the latest ESU (October 2026).
OAuth is an optional alternative to Basic authentication, not a replacement. No action is required, and your existing migration endpoints and in-progress migrations are not affected.
For step-by-step instructions, see Create migration endpoints with OAuth authentication | Microsoft Learn.
Exchange Online Migration Team
