The eDiscovery Challenge
During litigation holds, regulatory audits, or corporate investigations, legal teams are often handed massive archives of exported emails. Frequently, these arrive as thousands of individual `.msg` files.
For paralegals and junior associates tasked with first-pass review, MSG files present a unique logistical challenge: they are proprietary Microsoft files that typically require a full Outlook installation to open, read, and process.
Why Outlook is Problematic for Document Review
While it might seem logical to just use Outlook to review Outlook files, doing so in an eDiscovery context introduces several risks:
- Accidental Modification: Opening an MSG file in Outlook can inadvertently alter file metadata (like "Last Opened" dates), which can be disastrous for maintaining a strict chain of custody.
- Cloud Sync Risks: If the reviewing machine has an active Outlook account connected to Microsoft 365 or an Exchange server, there is a risk of accidentally syncing or leaking confidential discovery documents to the cloud.
- Licensing Bottlenecks: Not every contract reviewer or temporary paralegal has a dedicated Microsoft 365 license, creating unnecessary IT bottlenecks.
- Sluggish Performance: Outlook is a heavyweight email client, not a rapid-fire document viewer. Opening hundreds of individual MSG files one by one in Outlook is slow and prone to crashing.
Best Practices for MSG File Review
To maintain defensibility and speed up the review process, legal teams should adopt the following practices when handling native MSG files:
1. Operate in a "Sandboxed" Environment
Never review discovery documents on a machine with an active, personal email account logged in. Use dedicated, air-gapped, or strictly controlled review machines to prevent accidental data exfiltration or cloud syncing.
2. Preserve Original Metadata
Take cryptographic hashes of the original MSG files before you begin the review process. When opening files, ensure your viewing software does not write changes back to the file system.
3. Review Attachments Systematically
MSG files are often containers for other critical documents (PDF contracts, Excel spreadsheets, image evidence). When reviewing an MSG file, you need visibility into all embedded attachments — their names, types, and sizes.
4. Use a Dedicated, Offline Viewer
Instead of risking Outlook, organizations should deploy lightweight, purpose-built MSG viewers for their review teams.
Recommended Tool: OpenMSG for Legal
For law firms and compliance departments, OpenMSG provides a secure, defensible way to review native MSG files.
- Local Processing: OpenMSG has no cloud components and requires no internet connection to view MSG files. Email content stays on the review machine.
- Read-Only by Default: The application only reads MSG files; it does not modify original metadata or save changes back to the file.
- Instant Loading: Built with native Windows APIs, it opens even multi-megabyte emails in milliseconds, allowing reviewers to rapidly click through archives.
- Attachment Visibility: Reviewers can instantly see a list of all embedded attachments and extract them to a secure folder with a single click.
By moving away from heavy email clients and adopting purpose-built tools, legal teams can process MSG disclosures faster, securely, and at a fraction of the licensing cost.