Privacy-first, by default
Mbox Viewer is designed to treat privacy not as an option but as the starting point. Your archive never leaves your device.
- No uploadsprocessing happens in your browser; nothing is sent.
- No trackingno analytics, no telemetry, no ads, no third-party scripts.
- Open designManifest V3 with minimal permissions and audit-friendly code.
- Local storageemails, tags, notes and settings live in IndexedDB on your device.
External images and trackers blocked
In the preview, external images and hidden CSS trackers are blocked by default. Each message is also shown inside a locked-down frame, so any code hidden in a message can never run.
The main settings
| Setting | What it does |
|---|---|
| Theme | Light, dark or follow the system |
| Contrast | High contrast for better readability |
| Always load external images | Turns off the default blocking if you want |
| Embed external images in exports | Includes external images in exports |
| Reduce motion | Reduces animations |
| Display style | Default, Classic Outlook, Gmail, Thunderbird, Apple Mail or Forensic (monochrome) |
| In-memory mode threshold (GB) | Files below this limit load in RAM for speed, larger ones in the database |
| Clear local database | Removes all imported mail from your device |
| Export and import workspace | Take tags, stars, notes and saved searches to another device |
Storage and persistence
Your data lives in browser storage (IndexedDB). The browser sets its own limit, separate from free disk space. If you want, request persistent storage so the browser does not clear your data automatically under pressure. The extension shows how much storage you use and whether persistent storage was granted.
Working on a shared or public computer? When you are done, use Clear local database to remove all imported mail from that device.
Frequently asked questions
Are my emails stored anywhere off my device?
No. Everything is local in your browser. There is no server and no files are uploaded.
Does Mbox Viewer cost money or contain ads?
No. Every feature is free, and there are no ads, trackers or hidden costs.
How many languages is the extension available in?
Mbox Viewer is available in 22 languages, with light, dark and system themes and a high-contrast option.
How do I remove all imported mail again?
Go to Settings and choose Clear local database. That permanently removes all imported messages from your device.
Can I take my tags and notes to another computer?
Yes. Export your workspace through Settings and import it on the other device.
Why do I see Blocked script execution in about:srcdoc in the console?
That is not an error. Each message is shown in a locked-down frame so hidden code never runs. Chrome prints that note for every locked-down frame, even for a message with no code.
You can find shortcuts and error codes in error codes and troubleshooting.