Email Migration

Fix Gmail to Microsoft 365 Batch Migration Forwarding Errors

Maira Mehtab Sep 22, 2026 868 views

Question details

A Google Workspace to Microsoft 365 batch email migration fails during the completion stage due to forwarding verification and transient failure exceptions.

Product: Microsoft 365
Device & OS: not provided
Scenario: Migrating mailboxes from Google Workspace (Gmail) to Microsoft 365 using the batch migration tool.
Observed behavior: Mailboxes synchronize successfully at first, but the migration process fails at completion with TooManyTransientFailureRetriesPermanentException and GmailForwardingAddressRequiresVerificationException.

Before you start

Ensure you have Global Administrator privileges for your Microsoft 365 tenant, as you will need full administrative access to contact backend technical support.

Solution 1Recommended

Open a Microsoft 365 Service Request for Backend Review

Because these specific forwarding verification and retry exceptions are tied to backend restrictions, you must contact Microsoft technical support to bypass the blocks and clear the errors.

The GmailForwardingAddressRequiresVerificationException occurs because Google enforces strict verification for external forwarding addresses. When combined with transient failure retries, the migration batch gets permanently stuck.

Microsoft engineers have the necessary backend access to review the migration logs and manually unblock or approve the forwarding requirements that the automated batch process cannot handle.

Log in to the Admin Center

Go to the Microsoft 365 admin center and log in using your Global Administrator credentials.

Access Help and Support

Click on the 'Support' icon or navigate to 'Help & support' in the left-hand menu of the admin dashboard.

Submit the Error Details

Type a brief description of the migration failure into the search bar, then select the option to contact support. Provide the exact exception codes (TooManyTransientFailureRetriesPermanentException and GmailForwardingAddressRequiresVerificationException) in your ticket so the backend team can investigate.

Wait for Backend Resolution: Do not delete the migration batch while waiting for support. Microsoft engineers will need the existing batch logs to identify the exact point of failure.

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Frequently Asked Questions

What is the TooManyTransientFailureRetriesPermanentException error in Microsoft 365?

This error means the migration process encountered a temporary issue (like a timeout or throttling) too many times. Because the retry limit was reached, the system stopped attempting the migration, making the failure permanent. It generally requires backend intervention to reset or clear.

Why does the Gmail forwarding verification exception happen during migration?

Google Workspace implements strict security policies requiring users to verify external email addresses before automatic forwarding is permitted. During a batch migration cutover, Microsoft 365 attempts to set up forwarding automatically, which Google blocks if verification cannot be bypassed.

Can I fix these batch migration errors without contacting Microsoft Support?

Typically, no. While you can verify forwarding addresses manually in Gmail, the combination of transient failure lockouts and batch processing errors usually requires a Microsoft support engineer to clear the backend logs and force the synchronization to complete.

Migration & Recovery