MBOX Viewer

Overview

Open a whole mailbox in your browser. The .mbox file is read as a stream, so a large Gmail Takeout export lists its messages while it is still being read, and only the message you open is loaded. Search by sender or subject, read each message with its attachments and headers, and save messages as .eml, .emlx or a new .mbox. Nothing is uploaded.

Read a Gmail Takeout exportFind the message you need in years of exported mail without importing it anywhere.
Open a Thunderbird folderEach Thunderbird folder is an mbox file; open it directly, deleted messages hidden.
Recover single messagesSave the messages you need as .eml files that any mail program opens.

Key features

Opens .mbox mailboxes from Gmail Takeout, Thunderbird, Apple Mail and more
Reads the mailbox as a stream: only the message you open is loaded
Search by sender or subject; filter by Gmail label
Hides messages Thunderbird marked as deleted, or shows them
Each message with its headers, source, route and attachments
Save one message as .eml, .emlx or .mbox
Download every message as .eml or .emlx files in a ZIP, or as one .mbox
Drop several .eml, .msg or .emlx files to read them as one list
HTML mail shown safely: no scripts, remote images blocked until you allow them

Set

Document Tools 20

Neighbours

01 Invoice Builder 02 CSV to JSON Converter 03 CSV to XLSX Converter 04 Email Viewer & Editor 05 EML to MSG Converter 06 EML Viewer

Specification

Command: document.mbox_viewer
Set: Document
Input: MAIL/*
Output: MAIL/*
Max file: 16GB
Batch: yes

MBOX EML MSG EMLX

Runtime

Engine: SheetJS · Intl.Segmenter
Threads: single
Isolated: —
WebGPU: —
Memory: —

Transport 0 B

Your file is opened, worked on and saved inside this tab. This tool has no upload step, so your file has nowhere else to go.

Keys

Search: ⌘K
Panels: ⌘1 · ⌘2
Full width: F
All keys: ⌘/

How it works

Open a mailbox

Drop an .mbox file on the page. It is read in your browser, in the background, so a large export shows its first messages right away.

Find a message

Search by sender or subject, filter by label, and use the arrow keys to move through the list.

Read and look underneath

Each message opens with its attachments, headers, raw source and the route it took.

Save what you need

Save a message, its attachments, or the whole mailbox as separate .eml files.

Frequently asked

How big a mailbox can it open?

Up to 16 GB. The mailbox is read as a stream and only the message you open is loaded into memory, so even a large Google Takeout export works. Reading a very large file takes a moment; the list fills in while it reads.

Where do .mbox files come from?

Google Takeout exports Gmail as .mbox, Thunderbird keeps every folder as one, and Apple Mail and many other programs export to it. It is the oldest common mailbox format: all messages in one text file, one after another.

Is my mailbox private?

Yes. It is read in your browser and nothing is uploaded. Images that messages would load from the internet stay blocked until you choose to load them.

Can I split a mailbox into separate emails?

Yes. Download all messages as .eml files in one ZIP, or as .emlx files for Apple Mail. The MBOX to EML converter does this in one step.

Keys

Search: ⌘K
Panels: ⌘1 · ⌘2
Full width: F
All keys: ⌘/