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Migrating from Mail Archives (MBOX, EML, and MSG Archives)

This guide provides essential information for migrating MBOX, EML, and MSG email archives to Google Workspace or Microsoft 365.

PST Archives: Microsoft Outlook PST files are handled via a separate migration engine. For guidance on migrating PSTs, please refer to the general Migration Guide.

1. Prerequisites & Environment

To perform a Mail Archive migration, the following environment requirements must be met:

  • CloudM Migrate Self-Hosted: This source type is only supported on the self-hosted (Desktop/Server) version of CloudM Migrate.
  • CloudM Licensing: Licensing for Mail Archives to Google Workspace or Microsoft 365.
  • File Access: Archive files must be accessible via the local file system or a valid network path (UNC) from the machine running the application.
  • Service Account Permissions: The Windows service account running the CloudM Migrate Service must have Read access to the source archives and Write access to the path location if any log/index files are generated.

2. Supported Archive Formats

CloudM Migrate supports standard email archive formats including, but not limited to:

Format Details / Compatibility
MBOX Commonly exported from Google Takeout or Thunderbird. Includes variants: mboxrd, mboxo, mboxcl, and mboxcl2.
EML Standard individual email message files (RFC 822).
MSG Individual Microsoft Outlook message files.

3. Configuration Steps

Before starting, ensure your destination platform (Google Workspace or Microsoft 365) is fully authorized in the CloudM Migrate configuration wizard.

  1. Select Mail Archive as your Source Platform.
  2. Navigate to the Users (Items to Migrate) section.
  3. Configure your mapping table using the following parameters:
Field Value / Requirement
Export Type User
Export Name Source primary email address (e.g., user@source.com)
Import Type User
Import Name Destination primary email address (e.g., user@destination.com)
Archive Path The full local or UNC path to the file or directory (e.g., \\server\archives\user.mbox or C:\Archives\User_Folder\)

4. Important Considerations

  • Network Connectivity: If using network paths, we recommend UNC paths (\\Server\Share) over mapped drives (Z:\), as mapped drives may not be visible to the system service context. See Configuring Mapped Network Drives.
  • Folder Structures: When migrating a directory of EML or MSG files, CloudM Migrate will recreate the sub-folder structure in the destination mailbox based on the folder hierarchy in the source path.
  • Date Handling: CloudM Migrate extracts the "Date" header from the email metadata to ensure messages appear correctly in the destination timeline.

TIP: If the "Archive Path" column is not visible in your User list, click the Columns button in the grid view and ensure it is checked.

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