README
¶
msg-to-jsonl
Outlook MSG parser for shell pipelines.
Reads .msg files and outputs structured JSONL — one JSON object per message — to stdout.
Uses the same output schema as eml-to-jsonl,
so both tools compose naturally in the same pipeline.
Features
- Extracts headers:
from,to,cc,bcc,subject,date,message_id,in_reply_to,x_mailer - Handles Unicode (UTF-16LE) and codepage-encoded (String8) MAPI properties
- Decodes all text to UTF-8; records original charset in the
encodingfield when relevant - Supports Japanese charsets: Shift_JIS (CPID 932) and other Windows codepages
- Prefers SMTP addresses; silently discards X.400/Exchange internal addresses
- Structured To/CC/BCC split from MAPI recipient records
- HTML body decoding with UTF-16LE BOM and codepage detection
- Attachment metadata (filename, MIME type, size) — binary content not embedded
- Input: stdin, file arguments, or directory (processes all
*.msgin the directory) - No API keys or network access required — pure local parser
Installation
git clone https://github.com/nlink-jp/msg-to-jsonl.git
cd msg-to-jsonl
make build
# Add dist/ to PATH or copy dist/msg-to-jsonl to a directory on PATH
Usage
# Single file
msg-to-jsonl message.msg
# Multiple files
msg-to-jsonl mail1.msg mail2.msg
# Directory batch (all *.msg)
msg-to-jsonl ~/exported-mail/
# Stdin
cat message.msg | msg-to-jsonl
# Pretty-print for inspection
msg-to-jsonl --pretty message.msg
# Combine with eml-to-jsonl in the same pipeline
{ eml-to-jsonl inbox/eml/; msg-to-jsonl inbox/msg/; } | lite-llm -p "Summarise each email."
Output format
Each message produces one JSON line (identical schema to eml-to-jsonl):
{
"source": "inbox/message.msg",
"message_id": "<abc123@example.com>",
"in_reply_to": "<xyz@example.com>",
"from": "Alice <alice@example.com>",
"to": ["Bob <bob@example.com>"],
"cc": [],
"bcc": [],
"subject": "Hello World",
"date": "2026-03-27T10:00:00Z",
"x_mailer": "Microsoft Outlook 16.0",
"encoding": "Shift_JIS",
"body": [
{"type": "text/plain", "content": "Hello..."},
{"type": "text/html", "content": "<html>...</html>"}
],
"attachments": [
{"filename": "report.pdf", "mime_type": "application/pdf", "size": 102400}
]
}
Flags
| Flag | Default | Description |
|---|---|---|
-pretty |
false | Pretty-print JSON instead of JSONL |
-version |
— | Print version and exit |
Building
make build # current platform
make build-all # all release platforms → dist/
make test # run tests
make check # vet + lint + test + build + govulncheck
Documentation
- docs/design/overview.md — architecture and design decisions
- docs/dependencies.md — third-party dependencies
Part of util-series
msg-to-jsonl is part of the util-series — a collection of lightweight CLI tools for working with local and cloud LLMs.
Documentation
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