OmniCastCONVERTER
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Universal workbench

MBOX mailbox to Email JSON

Create Email JSON from MBOX mailbox locally, with no upload or account.

Device-onlyNo uploads. Ever.
Pipelines, branches, presets, naming, and detailed controls
Display
Quick start
Help me choose the best output Suggested: Email JSON

Recommendations use the registered target format and tested fidelity classification. They never inspect or upload your content.

01Input
Drop files or a folder hereChoose MBOX mailbox files or a folder — batch input is welcome
or paste content
238 chars · 8 lines · 238 B
02Configure & run
MBOX mailboxEmail JSON
structural conversion · single or batch
Conversion preflightSize, memory, engine, execution, and fidelity before you start
Input
238 B
Estimated peak memory
16 MiB
On-demand download
No large engine download
Execution
Responsive local worker
Fidelity
No lossy step declared
What to providePaste MBOX mailbox content or drop a matching file.What you’ll getProduces previewable Email JSON text and a correctly named download.
Output naming & batch behavior
Exampleoutput.email.json
Pipeline 1 linear · 0 branches
Why use A → B → C?

A pipeline feeds each result directly into the next compatible converter. Use one when the destination needs an intermediate representation or when you want to inspect and normalize that middle format.

  • JSON → CSV → XLSX turns records into rows before building a workbook.
  • Markdown → HTML → DOCX resolves markup before creating a document.
  • SVG → PNG → PDF intentionally flattens vector artwork before placing it on a page.
Only type-compatible next steps are offered. Lossy steps are marked before you run them.
1MBOX mailbox to Email JSONstructural
Parallel output branchesEach branch receives the final linear result. Branches do not feed or depend on one another.
Processing happens locally. Your file bytes are never sent anywhere.
About this conversion

How to convert MBOX mailbox to Email JSON

Before you start

Paste MBOX mailbox content or drop a matching file.

Accepted: .mbox · application/mbox
  1. Paste valid MBOX mailbox content, choose files, or drag them onto the drop zone.
  2. Confirm the detected format. Mixed-format batches are flagged before conversion.
  3. Select “Convert on this device.” Produces previewable Email JSON text and a correctly named download.

How this converter behaves

The source records are parsed into a small, typed interchange model and serialized into the destination format with explicit fidelity limits.

What happens to your data?

The conversion engine runs in this browser tab. OmniCastConverter has no upload API and never sends your content, file name, or converted result to a server.

Fidelity and limitations

This route is classified as structural. The converter preserves meaning and structure supported by both formats.

  • The normalized representation preserves common address, subject, date, message ID, and readable body fields. MIME attachments, rich HTML alternatives, signatures, DKIM results, and provider-specific headers are not preserved.

Try a valid example

The “Use example” action in the workbench loads this exact input. Produces previewable Email JSON text and a correctly named download.

From ada@example.com Thu Jul 23 09:00:00 2026
From: Ada <ada@example.com>
To: local@example.test
Subject: Private conversion
Date: Thu, 23 Jul 2026 09:00:00 +0000
Message-ID: <local-example@example.com>

This mailbox stays in the browser.