The fastest way to read MBOX files on your Mac
Back up your Gmail with Google Takeout and read it offline on your Mac. Open, search, and export emails from MBOX and EML archives of any size.
We only store your email. No spam, ever.
Mbox Viewer — three-column layout with message list, Gmail labels, and text view.
Why Mbox Viewer?
Your Gmail, offline on your Mac
Use Google Takeout to back up your entire Gmail account. Mbox Viewer lets you read, search, and browse those backups offline — no internet required.
Other tools choke on large files
Most MBOX readers crash or freeze on files over a few hundred MB. Many use Electron or Java.
Built specifically for this
Mbox Viewer streams through files of any size without loading them into memory. Native macOS, instant search, full export.
Features
Handles any size
Streaming parser with 1 MB buffer. Opens files from a few KB to 50+ GB without loading the entire file into memory.
Instant re-opens
Binary index with SHA-256 validation. First open indexes the file; subsequent opens take under 1 second for any size.
Powerful search
Full syntax: from:, to:, subject:, body:, date:, has:attachment, label:, size:>, OR, negation, exact phrase.
Gmail labels
Automatically reads Gmail labels from Google Takeout. Browse by label in the sidebar with message counts.
Full export
Export to EML, CSV, plain text, or extract all attachments. Merge multiple MBOX files with deduplication.
Conversation threads
JWZ threading algorithm groups messages into conversations with visual reply chains up to 4 levels deep.
Native macOS
SwiftUI + AppKit. Dark mode, Drag & Drop, Quick Look, Share, Print. No Electron, no Java, no web wrapper.
Privacy first
Everything runs locally on your Mac. No cloud, no telemetry, no data leaves your machine. Ever.
Export labels to MBOX
Export any Gmail label as a standalone MBOX file. Create smaller, focused archives from your full Gmail backup.
Print & Share
Print messages with formatted headers. Share via Mail, AirDrop, Notes, and other macOS share services.
Attachments
View attachments inline, preview with Quick Look (Spacebar), save individually or in bulk, drag directly to Finder.
Drag & Drop
Drop MBOX or EML files onto the app to open them. Drag messages out as .eml files or drag attachments to Finder.
Performance
Opens a 50 GB MBOX file in under 5 minutes. Re-opens it in under 1 second.
| File Size | Messages | First Open | Re-open | RAM Usage |
|---|---|---|---|---|
| 500 MB | ~5,000 | < 5 sec | < 1 sec | < 100 MB |
| 5 GB | ~50,000 | < 30 sec | < 1 sec | < 200 MB |
| 50 GB | ~500,000 | < 5 min | < 1 sec | < 600 MB |
Re-open is always under 1 second regardless of file size, thanks to the binary index.
Pricing
Free
- Up to 500 MB
- All features included
Annual
- Unlimited file sizes
- 3 device activations
Lifetime
- Unlimited file sizes
- 3 device activations
All purchases include a license key for 3 devices.
Payments processed securely by Lemon Squeezy (a Stripe company). VAT included.
Need more licenses or activations? Contact us.
Get Early Access
Be the first to know when Mbox Viewer is ready. Subscribe to receive early access to the first version.
We only store your email. No spam, ever.
Search Syntax
Powerful search with full query syntax. Use the search bar or the visual filter sheet (Cmd+Shift+F).
Show full search syntax reference Hide search syntax
| Prefix | Example | Description |
|---|---|---|
| from: | from:[email protected] | Messages from this sender |
| to: | to:team@ | Messages sent to this address |
| cc: | cc:manager | Messages CC'd to this person |
| subject: | subject:"quarterly report" | Subject contains phrase |
| body: | body:invoice | Full-text body search (press Enter) |
| has:attachment | has:attachment | Messages with attachments |
| has:no-attachment | has:no-attachment | Messages without attachments |
| label: | label:Important | Gmail label |
| filename: | filename:report.pdf | Attachment filename |
| date: | date:2024-03 | Messages from March 2024 |
| before: | before:2024-01-01 | Messages before date |
| after: | after:2023-06-15 | Messages after date |
| size:> | size:>5mb | Messages larger than 5 MB |
| size:< | size:<100kb | Messages smaller than 100 KB |
| - | -spam | Exclude term |
| "..." | "exact phrase" | Exact phrase match |
| OR | from:alice OR from:bob | Either condition |
| (implicit) | invoice 2024 | Both terms (AND) |