What's new in Mbox Viewer

Merging mailboxes, rebuilt

• Fixed Merging Apple Mail mailboxes tagged every message with the same origin. Apple Mail's "Export Mailbox…" writes a folder named "Inbox.mbox" containing a file called literally "mbox", so the optional X-Mbox-Source header recorded "mbox" for all of them — losing the whole point of the option, which is knowing which archive an email came from. Merged messages now carry the name you recognize, and mailboxes that would share a name are told apart by their folder.
• Improved Merging no longer requires opening a mailbox first. It is now an app-level action with its own window, available from File → Merge MBOX Files… and from a button on the welcome screen. If a mailbox is already open, it starts out in the list.
• Improved The merge window is far more usable: the list scrolls instead of pushing the window off-screen, shows each mailbox's size and a total, accepts mailboxes dropped onto it, and reports real progress while it works ("Merging 2 of 5 — Inbox.mbox"). When it finishes it tells you how it went in your own language and offers Show in Finder, Open Merged Mailbox and Close.
• Improved The toolbar explains itself. Conversation threading no longer shares an icon with Search Filters — it now uses the conversation bubbles Mail.app uses for the same thing — and the six icon-only view segments (Text, Full Headers, Properties, MIME, Raw, Hex) name themselves on hover, shortcut included: "Full Headers (⌘2)".
• Fixed Menu items that need an open mailbox — File → Export, the View and Message commands, Search Filters — are greyed out with none open, instead of looking available and being silently ignored when clicked.

The search field no longer disappears while you type

• Fixed The search field no longer vanishes from the toolbar while you type. At certain window widths, entering a query could push it out of view with no way to bring it back until you resized the window. It now keeps a fixed width; the match count is still shown in the status bar.
• Fixed ⌘F now always leads somewhere: if the search field can't be focused, it opens the Search Filters panel instead of doing nothing.

Export to PDF and HTML, repair damaged mailboxes, and new inspection views

• New Export any message to PDF. The exported PDF keeps the same layout as printing, in a self-contained multi-page file. Exporting one message is free; batch PDF export (several at once) is a Pro feature.
• New Export any message to a self-contained HTML file — headers, body with inline images embedded, and attachments included as downloadable links — so it opens anywhere with no external references. Single-message export is free; batch export is Pro.
• New New attachments pane: a gallery that lists every attachment with a per-type icon, its content type and size, image preview and one-click save — including “Save all” to a folder.
• New Three new ways to inspect a message, alongside Text and Headers: a Properties view (all addresses, dates and threading identifiers, selectable and copyable), a MIME structure view (the message's part tree with content types, encoding, charset and sizes) and a Hex view (an offset · hex · ASCII dump of the raw message) — ideal for technical or forensic inspection.
• New Repair damaged mailboxes (Pro). When a mailbox opens empty or as one giant message, its “From ” separators were probably lost; a deep-scan recovery re-detects the message boundaries. You can rebuild the view in place or export a brand-new, repaired .mbox copy — and the original file is never modified (the app stays strictly read-only).
• Improved Merge mailboxes with full traceability: a new option adds an “X-Mbox-Source” header to each merged message with its origin file name, so a combined archive still shows which mailbox every email came from. Off by default, and it works with or without duplicate removal.

Merge Mailboxes fixes and a 1 GB free limit

• Fixed The “Merge Mailboxes” picker no longer greys out your mailboxes: you can now select any recognizable mailbox — including extensionless Thunderbird mailboxes (INBOX, Sent…), .mbs/.mbx archives, files on a NAS, and Apple Mail “Name.mbox” export folders.
• New Merging up to 1 GB of combined mailboxes is free; larger merges are now a Pro feature, shown with a clear notice and an upgrade option.

Faster, more private, more accessible

• Improved Faster on large mailboxes: quicker searching, lower memory use, and no more UI freezes when opening very large messages or exporting.
• Security More private: remote images (tracking pixels) are blocked more thoroughly, temporary files are cleaned up automatically, and new Settings let you clear your search history and index cache.
• Improved More accessible: full VoiceOver and keyboard support, adjustable message text size and font, better contrast, and the in-app language picker now lists all 18 languages.
• Fixed More robust: handles malformed or oversized MBOX/EML files gracefully instead of freezing or crashing, and export/merge failures are now clearly reported.
• New HTML messages now show the sender header and quick actions (Export, Print, Share) at the top, just like plain-text messages.

Full Headers view and 8 new languages

• New New Full Headers view: see the complete header block (From, To, Cc, Date, Message-ID, Reply-To and more) in a clean, read-only pane. Pick it from the toolbar (Text / Headers / Raw) or from View → Full Headers (⌘2). Thanks to Verender Badial for the suggestion.
• New Eight new languages — Simplified Chinese, Traditional Chinese, Turkish, Swedish, Danish, Norwegian, Russian and European Portuguese — bringing the app to 18 languages.

Apple Mail and Thunderbird exports open directly

• New Apple Mail export folders (.mbox packages) now open directly — no need to dig out the inner “mbox” file.
• New Mailbox files without an extension — like Thunderbird's INBOX or Sent — open directly, no renaming to .mbox required.

Safer HTML and smarter search

• Security Email HTML is now sanitized before display — scripts, iframes and other active content are stripped, on top of the existing remote-image blocking.
• Improved Free-text search now looks inside message bodies too, not just subject and sender — so a plain word finds everything.
• Fixed Hardened parsing of very large files so a message split across read buffers can never inflate the message count.

Accurate version info and code redemption

• Fixed The About window now always shows the real installed version.
• New Added a «Redeem Code» button so you can use Mac App Store promo codes for the Pro upgrade.

Pro is now a simple one-time purchase

• Improved Streamlined the App Store edition to a single lifetime Pro unlock. The upgrade screen now loads its price instantly.

Clearer upgrade path

• New Added an «Upgrade to Pro» banner on the welcome screen so unlocking unlimited file size is one tap away.
• Fixed Several refinements to the purchase and restore flow.

New Window shortcut and legal links

• New Added a New Window command (Cmd+N) and quick links to the Privacy Policy and Terms.
• Improved Clicking the Dock icon with no windows open now reopens the welcome window.

Mbox Viewer arrives on the Mac App Store

• New First Mac App Store release, with sandboxing and automatic updates through the App Store.
• Fixed Resolved several export and save-panel issues for a smoother experience.

Now speaking ten languages

• New Added German, French, Italian, Japanese, Korean, Dutch, Polish and Brazilian Portuguese — full UI and user guide.

Mbox Viewer 1.0 — the first release

• New Streaming MBOX and EML reader that opens files of any size without loading them into memory, with an instant-reopen binary index.
• New Powerful search syntax, Gmail labels, conversation threading, and export to EML, CSV, text and attachments.
• New Fully native macOS app — SwiftUI + AppKit, dark mode, Drag & Drop, Quick Look, Share and Print.

Traceable merges, with real progress and an explanation

• Fixed Merging mailboxes exported from Apple Mail tagged every message with the same origin. Apple Mail exports each mailbox as a folder named "Inbox.mbox" containing a file called literally "mbox" — and that inner file is the one the app opens, so the X-Mbox-Source header recorded "mbox" everywhere and the combined archive lost the traceability the header exists for. It now records the name you recognize, and mailboxes that would share a name are told apart by their folder ("Work/Inbox.mbox").
• Improved Merging shows real progress and says where the file ended up. The bar used to be indeterminate with a fixed label even though the engine reports progress; it now names each mailbox as it goes ("Merging 2 of 5: Inbox.mbox", the same name that gets written into the header), and when it finishes the status bar shows the full path of the merged file — before, you only saw its name in the tab.
• Improved Every toolbar control now has a tooltip. Fifteen of them had no explanation at all — the search box, the sort dropdown, the three welcome-screen buttons, the eight viewer tabs and the two buttons on each attachment — and Export and Print now show their shortcut (Ctrl+E / Ctrl+P).
• Improved The Help now explains merging and the source-mailbox header. A new "Merge mailboxes" section covers how merging works, what "Remove duplicates" does, what the X-Mbox-Source checkbox writes and how to see that header in a message (the Headers tab). The checkbox's own help text said "the source file name"; it now says "mailbox", which is what it actually writes.
• Fixed "Repair mailbox" and "Export repaired copy" are no longer dead clicks. In the settings menu they were always enabled, but with no mailbox loaded in the active tab they did nothing and said nothing; they are now disabled until they can work. Merge stays available, because it works with or without an open mailbox.

Export to PDF and HTML, repair damaged mailboxes, and new inspection views

• New Export any message to PDF. The exported PDF keeps the same layout as printing, in a self-contained multi-page file. Exporting one message is free; batch PDF export (several at once) is a Pro feature.
• New Export any message to a self-contained HTML file — headers, body with inline images embedded, and attachments included as downloadable links — so it opens anywhere with no external references. Single-message export is free; batch export is Pro.
• New New attachments pane: a gallery that lists every attachment with a per-type icon, its content type and size, image preview and one-click save — including “Save all” to a folder.
• New Three new ways to inspect a message, alongside Text and Headers: a Properties view (all addresses, dates and threading identifiers, selectable and copyable), a MIME structure view (the message's part tree with content types, encoding, charset and sizes) and a Hex view (an offset · hex · ASCII dump of the raw message) — ideal for technical or forensic inspection.
• New Repair damaged mailboxes (Pro). When a mailbox opens empty or as one giant message, its “From ” separators were probably lost; a deep-scan recovery re-detects the message boundaries. You can rebuild the view in place or export a brand-new, repaired .mbox copy — and the original file is never modified (the app stays strictly read-only).
• Improved Merge mailboxes with full traceability: a new option adds an “X-Mbox-Source” header to each merged message with its origin file name, so a combined archive still shows which mailbox every email came from. Off by default, and it works with or without duplicate removal.

Merge from settings, safer viewer and a more reliable engine

• New Combine mailboxes right from the settings (⚙) menu — including the mailbox you already have open. Merging up to 1 GB combined is free; Pro unlocks larger merges.
• Improved More reliable: merging never leaves a corrupted file, message dates display more accurately, and very large or damaged mailboxes are handled safely.
• Security Stronger security: the email viewer now blocks all remote and local-network content (tracking pixels and file/UNC links), preventing information leaks.

More formats, sort by recipient and safer HTML

• New Open more mailbox formats: Apple Mail, Thunderbird, and .mbs/.mbx files — plus a new “Open folder…” command and folder drag-and-drop.
• New New “Sort by recipient (To)” option in the message list.
• Security Stronger security: email HTML is now sanitized before it is displayed (scripts and remote content are blocked).
• Fixed Various improvements and fixes.

Mbox Viewer arrives on Windows

• New A native Windows app (WinUI) is coming to the Microsoft Store, built on the same streaming engine that opens MBOX and EML files of any size — up to 50 GB — without loading them into memory.
• New Feature parity with the Mac app: powerful search, Gmail labels, conversation threading, export to EML/CSV/text, 18 languages and the same Free / Pro one-time purchase.

Windows port begins in the lab

• New We start building the native Windows port: a WinUI 3 app (Windows App SDK) written in C# 12 / .NET 8, with WebView2 (Edge Chromium) rendering the email HTML in isolation.
• New It reuses the same streaming approach as the Mac app — opening huge MBOX/EML files without loading them into memory — and will ship as an MSIX package on the Microsoft Store, with the Pro unlock via Windows.Services.Store.