Google Vault to Office 365 Migration Without Data Loss Fast!

Organizations often use Google Vault to export employee mailbox data for compliance, legal hold, backup, or migration purposes. Google Vault mainly exports email data in two formats: MBOX and PST. Since Microsoft 365 (Office 365) natively supports PST files, importing PST data is relatively straightforward. However, when users export data in MBOX format, additional steps are required before migration.

This guide explains both methods in a simple and direct manner.

Method 1: Import Google Vault PST Files into Office 365

If your Google Vault export is already in PST format, Microsoft provides a native import method through the Microsoft Purview compliance portal.

Step 1: Prepare the PST File

1. Download the Google Vault export.
2. Extract the ZIP file if compressed.
3. Verify the PST file opens correctly in Microsoft Outlook.

Step 2: Upload PST File to Azure Storage

1. Open the Microsoft Purview portal.
2. Navigate to:
3. Data Lifecycle Management → Import
4. Create a new PST import job.
5. Download the Azure AzCopy tool and the SAS URL provided by Microsoft.
6. Upload the PST file to Microsoft’s temporary Azure storage location.

Step 3: Create PST Mapping File

1. Download the sample CSV mapping file.
2. Map each PST file with the target Office 365 mailbox.
3. Save the CSV file.

Step 4: Start the Import Process

1. Upload the CSV mapping file.
2. Validate the mappings.
3. Start the import job.

Microsoft 365 will begin importing mailbox data into the assigned user accounts.

This method works well when the export is already in PST format and Outlook compatibility is required.

Method 2: Import Google Vault MBOX Files into Office 365

Google Vault frequently exports mailbox data in MBOX format, especially when exporting large user mailboxes. Since Office 365 does not directly support MBOX files, users must first migrate or convert the data.

Manual Approach Using Thunderbird and Outlook

Step 1: Install Thunderbird

1. Install Mozilla Thunderbird email client.
2. Add the ImportExportTools NG add-on.

Step 2: Import MBOX Files into Thunderbird

1. Right-click Local Folders.
2. Choose:
3. ImportExportTools NG → Import MBOX File
4. Load the Google Vault MBOX files.

Step 3: Move Emails to Outlook

1. Configure the same Office 365 account in Outlook.
2. Drag emails from Thunderbird to Outlook manually using EML export or IMAP synchronization.

Limitations of Manual Method

1. Time-consuming for large mailboxes.
2. Multiple conversion steps involved.
3. Risk of folder hierarchy changes.
4. Difficult to handle bulk MBOX files.
5. Requires technical effort and Outlook configuration.
6. Professional Method for Google Vault MBOX to Office 365 Migration

For direct migration, users can use the BitRecover MBOX to PST Converter and Office 365 migration solution. The tool allows users to import Google Vault MBOX files directly into Office 365 accounts using secure Microsoft Graph API authentication. It supports bulk migration, maintains folder hierarchy, provides preview and advanced filter options, and also includes IMAP support for flexible migration workflows. Users can additionally convert MBOX to PST format when required for Outlook-based imports or backup purposes.

Final Words

Importing Google Vault data into Office 365 depends mainly on the export format. PST files can be directly imported using Microsoft’s native PST import service. However, MBOX exports require additional processing because Office 365 does not support MBOX files directly. While manual methods are available, they become difficult for large-scale migrations. In such cases, a dedicated MBOX to PST converter and Office 365 migration solution helps simplify the process while preserving mailbox structure and data integrity.