Open source · MIT
mboxShell
The free terminal tool behind Mbox Viewer. Open, search and export MBOX files of any size — right from your shell, on Linux, macOS, FreeBSD and Windows.
What it does
A full MBOX toolkit in your terminal
Everything you need to work with huge email archives — reading, searching, threading and exporting — with no GUI and no cloud.
Any file size
A streaming parser with a 1 MB buffer opens 50 GB+ Gmail Takeout backups while keeping RAM around 500 MB.
Sub-second re-opens
A persistent binary index — verified with SHA-256 — reopens even the largest archive in under a second.
Field-based search
Filter with from:, subject:, date:, body:, has:attachment and label:, plus OR and exact phrases — in the TUI or from the command line.
Gmail labels
Detects X-Gmail-Labels and turns them into virtual folders you can browse and filter by.
Conversation threading
Groups related messages into conversations using the classic JWZ threading algorithm.
Export anywhere
Save messages as EML, CSV, TXT or HTML, and extract attachments individually or in bulk.
Merge & dedupe
Combine several MBOX files into one, with optional deduplication so nothing is imported twice.
Full terminal UI
A ratatui-based TUI with three layout modes, vi-style navigation and shell completions for bash, zsh, fish, PowerShell and elvish.
Cross-platform & bilingual
A single ~5 MB binary with no runtime dependencies. Runs on Linux, macOS, FreeBSD and Windows, with an English/Spanish interface.
Latest version
What's new in v0.6.0
An interactive-performance release for very large mailboxes, released on July 3, 2026.
- The message view no longer re-wraps the whole body on every frame — styled lines are cached and reused.
- Incremental search is debounced into a single pass that runs after typing settles (~150 ms).
- Selecting a message no longer deep-copies its decoded body; bodies are shared by reference for cheaper selection.
Usage
One command away
- $ mboxshell archive.mbox
- # Open the interactive terminal UI
- $ mboxshell search archive.mbox "from:jane has:attachment"
- # Search straight from the command line
- $ mboxshell export archive.mbox -f eml -o out/
- # Export messages to EML, CSV, TXT or HTML
- $ mboxshell merge a.mbox b.mbox -o all.mbox --dedup
- # Merge files, removing duplicates
- $ mboxshell attachments archive.mbox -o files/
- # Extract every attachment at once
Install it
Grab a pre-built binary for Linux, macOS, FreeBSD or Windows from the releases page, or build it yourself with Cargo:
$ cargo install --git https://github.com/dcarrero/mboxshell.gitFrom CLI to app
The open-source engine behind Mbox Viewer
Mbox Viewer for Mac and Windows grew out of mboxShell. The app wraps the same idea — reading MBOX files of any size, fully offline — in a polished native interface with search, labels, threading and EML support. Prefer the terminal? mboxShell is free and MIT-licensed.
github.com/dcarrero/mboxshell