I built this tool to solve a specific problem: searching through tens of thousands of emails to find the ones that matter — and exporting them cleanly as PDFs for legal or compliance use.
If you’ve ever had to respond to a litigation hold, conduct an internal investigation, or review a contract dispute, you know the pain. Gmail’s search is fine for day-to-day use. It is not designed for discovery.
There are other MBOX viewer tools out there. I tried them. The problem is that real-world MBOX files — especially Gmail Takeout exports from active accounts — can be multi-gigabyte files with tens of thousands of emails. Most tools choke on them. They freeze, crash, or simply never finish loading. I needed something that could handle the size without drama. So I built it myself.
This tool is lightweight, fast, and built for exactly this one job. It indexes your MBOX file once, then searches in seconds — no matter how large the archive. No bloat, no subscription, no cloud upload. Everything stays on your machine.
What Is an MBOX File?
An MBOX file is the standard format used by Gmail Takeout, Thunderbird, Apple Mail, and most other email clients to export or archive email. If you have ever downloaded your Gmail data through Google Takeout, you have an MBOX file. The problem is that these files can contain tens of thousands of emails, and there is no easy built-in way to search through them on Windows. You cannot just open them and Ctrl+F your way to the email you need.
This tool solves exactly that. Point it at your MBOX file, type a keyword, a name, a date range — and it finds the emails instantly.
What It Does
The Legal Email Discovery Tool searches one or more MBOX files — Gmail Takeout exports, Thunderbird archives, or any standard .mbox file — for emails matching your criteria, then exports each matching email as a properly formatted PDF.
- Filter by sender, recipient, subject, body text, or date range
- Combine multiple conditions: AND within a group, OR between groups
- Handles archives of any size — tested on multi-GB files
- Builds a persistent SQLite index so repeat searches take seconds
- Crash-safe: saves progress every 50 messages and resumes where it left off
- Outputs one PDF per matching email, plus a CSV log with full metadata
- Works out of the box with Gmail Takeout exports
Who It’s For
Free for personal use. If you’re a law firm, litigation support provider, or using it professionally, a commercial license is available for $20/year — which also gets you a stamped, verifiable license on every PDF you produce.
How to Get It
Download the zip file below. It includes a standalone Windows executable (no Python required), a Python script version for technical users, and a full README with step-by-step instructions.
⬇ Download Legal Email Discovery Tool v1.6
Windows 10/11 64-bit. Free for personal use.