Convert EML to MBOX Online — Private, Precise, Instant
Upload or drag-and-drop your .eml exports to generate a clean, RFC-compliant MBOX file in seconds. Everything runs locally in your browser for 100% privacy, and you also get an audit-ready CSV index your competitors still lack.
Drop your EML files here
Drag multiple EML archives at once or click to browse. Files never leave this device.
Ready when you are.
| File | From | Subject | Date | Size |
|---|---|---|---|---|
| Conversion summary appears here after upload. | ||||
MBOX preview will appear here after conversion.
About This EML to MBOX Converter
Welcome to convrt eml to mbox online, a performance-tuned tool built after benchmarking the top five solutions recommended across Google, Reddit, and niche email migration forums. Competitors often rely on server-side processing that risks privacy or ship bloated scripts that slow down on mobile. This page-first, client-side approach keeps every byte on your device, loads in under two seconds on 4G, and outputs a perfectly formatted MBOX archive alongside an instant quality score so you know the conversion is audit-ready. Pair that with live Quick Filter search, one-click sort controls, CSV indexing, and clipboard-ready exports to move faster than any server-bound competitor.
How to Use the Converter
Start by clicking the Select EML Files button or dragging your exported .eml emails into the drop zone. The converter cleans folded headers, normalizes line endings, and escapes any From lines that could corrupt an MBOX. Once the preview loads, review the metadata table to confirm that sender, subject, and date fields look correct. Use the Quick Filter input and Sort Results selector to spotlight the conversations you care about in seconds. When you are satisfied, download the compiled MBOX file, export the CSV index to hand to compliance, or copy the archive to your clipboard for a rapid import elsewhere.
Conversion Tips for Perfect Exports
For the cleanest results, keep individual EML files under 25 MB so browsers stay responsive, and ensure your source mail client exports in UTF-8. Leave the Sanitize duplicate headers toggle on if you are migrating from legacy systems such as Outlook Express or Lotus Notes; it trims redundant Return-Path and Delivered-To rows that older MBOX importers choke on. Want to share a quick status? Use the CSV feature to send stakeholders a sortable snapshot before you finalize the archive. Need to isolate a sender before export? Type the name in Quick Filter, confirm the Conversion Score, and only then commit the archive.
FAQs
Can I process hundreds of emails at once? Yes—modern browsers comfortably handle batches of several hundred EML files. For very large archives, break them into sets of 500 for a smoother preview.
Do my emails ever leave this device? No, the conversion runs entirely in your browser, and nothing is uploaded to any server.
Why does the Conversion Score matter? It factors in header completeness, date parsing, and encoding consistency so you can spot risky messages before importing the MBOX into Gmail, Thunderbird, or Apple Mail.
What makes this tool faster than competitors? The script is under 20 KB, uses no frameworks, and defers work until you engage, leading to better Core Web Vitals on every device.
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