// Private beta — Spring 2026
A modern mbox viewer.
Built for speed.
Drop in a Gmail Takeout, a legacy Unix mailbox, or a forensic archive. Read it in software that feels like this decade — not the last one.
// Still opening .mbox files in…
- Systools MBox Viewer
- Thunderbird
- Mutt
- mbox-util
- mbox2eml
The tools haven't moved in twenty years. We thought they should.
// 02 — What's inside
Fast, searchable, actually readable.
// 03 — Questions
What people ask before signing up.
What is an mbox file?
An mbox file is a plain-text mailbox format that stores multiple email messages in a single file, separated by 'From ' lines. It is defined by RFC 4155 and is the standard archive format used by Gmail Takeout, Thunderbird, macOS Mail, Mutt, and most Unix-style mail systems.
How do I open an mbox file from Gmail Takeout?
Gmail Takeout exports each label as a single .mbox file. tomorrow-box opens that file directly — no import step, no conversion to EML or PST. Drop the file into the reader and browse, search, or thread your messages.
What is tomorrow-box?
tomorrow-box is a modern mbox viewer built to replace two-decade-old tools like Thunderbird, Mutt, and legacy mbox utilities. It reads Gmail Takeout archives, Unix mail spools, and forensic mbox files in software designed for today's hardware.
Is tomorrow-box available now?
tomorrow-box is in private beta during Spring 2026. Join the waitlist to receive an invite when seats open.
What mbox sources does tomorrow-box support?
tomorrow-box reads mbox files from Gmail Takeout, Thunderbird profiles, macOS Mail exports, Unix mail spools (/var/mail), and forensic archives produced by e-discovery tooling.
// 04 — Sign up