categories.email.mbox
MBOX viewer
About MBOX
Unix mailbox — concatenated emails.
MBOX is a flat file of RFC822 messages separated by lines beginning with 'From ' (with a trailing space) — the classic Unix mailbox format that mutt, mh, alpine, and Thunderbird's Local Folders all use. We split the file at those separator lines and parse each chunk lazily with postal-mime as you click through the sidebar, which keeps even thousands-of-message archives responsive. The list shows From / Subject / envelope date pulled cheaply from the raw text; selecting a message triggers a full MIME parse for HTML/plain bodies and attachments. The filter box scans the first 4 KB of each message's headers (Subject, From, Date) for substring matches.
FAQ
- How do I get an .mbox file?
- Most Unix mail clients write it natively (mutt, alpine, mh). Thunderbird exports its Local Folders as mbox via the ImportExportTools NG extension. Google Takeout returns Gmail archives as a single .mbox per label.
- Why is the message list fast but opening a message takes a moment?
- We split the file by 'From ' lines up front (cheap text scan) and only parse the MIME body when you click a message. This keeps the sidebar instant on huge archives — the per-message parse runs in the background and the body appears as soon as it's ready.
- Are attachments shown?
- Yes. Each opened message lists its attachments with filename, MIME type, and size, and offers a Save button that downloads the attachment to your machine. The HTML body renders in a sandboxed iframe with all script and network access disabled.
- Is my mailbox uploaded?
- No. The .mbox file is read entirely in your browser. postal-mime and the splitter both run client-side. Nothing is sent to a server.
More categories.email