The Document Review Challenge
During regulatory audits, litigation, 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 a legal document review context introduces several risks:
- Accidental Modification: Opening an MSG file in Outlook can inadvertently alter file metadata (like "Last Opened" dates), which can compromise document integrity.
- 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 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
Legal teams should adopt the following practices when handling native MSG files:
1. Operate in a "Sandboxed" Environment
Review documents on dedicated, air-gapped, or strictly controlled machines to prevent accidental data exfiltration or cloud syncing.
2. Preserve Original Metadata
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 relying on 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 an efficient way to review native MSG files.
- Local Processing: MSG files are parsed entirely on the review machine — email content is never uploaded. The app collects anonymous usage analytics (opt-out available via registry policy for enterprise deployments).
- 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 files faster, securely, and at a fraction of the licensing cost.