Extract a saved email's plain-text body

Before you begin

Python 3.12 or newer

What this script changesReads local exports and creates a separate result, refusing overwrite. EML files are capped at 25 MiB; MBOX exports at 100 MiB and 5000 messages. Output can contain private message text and addresses. Drafts are local .eml files and are never sent. Attachment files are copied as data and never executed.

Set up your example

Save the complete code as eml-extract-text.py in a working folder.
Save the provided sample files in that same folder; run commands from that folder.

Sample files in this download:

sample.eml
sample.mbox
body.txt
note.txt

Download the ZIP, extract it, and open a terminal inside the extracted folder. The source file is eml-extract-text.py.

Run the script

python "eml-extract-text.py" --input "sample.eml" --output "body-copy.txt"

If your system uses python3 instead of python, use that command for Python examples. Keep paths containing spaces in quotes. Required inputs and optional settings are described in the code and setup steps.

What to expect

Save only the preferred plain-text body from an EML file. The output begins Hello Bo and excludes the attached notes.txt.

The complete script

#!/usr/bin/env python3
"Extract a saved email's plain-text body"
import argparse
import json
from pathlib import Path

def write_json(path, value):
    data = json.dumps(value, indent=2, ensure_ascii=False, allow_nan=False) + "\n"
    with Path(path).open("x", encoding="utf-8", newline="") as handle:
        handle.write(data)

import re
import hashlib
import mimetypes
import mailbox
from collections import Counter, defaultdict
from datetime import datetime, timezone
from email import policy
from email.parser import BytesParser
from email.message import EmailMessage
from email.utils import getaddresses, parseaddr, formataddr, parsedate_to_datetime, format_datetime, make_msgid

def raw(path,limit=25*1024*1024):
    if Path(path).stat().st_size>limit: raise ValueError("Input exceeds the size limit.")
    return Path(path).read_bytes()
def message(path):
    return BytesParser(policy=policy.default).parsebytes(raw(path))
def messages(path):
    if Path(path).stat().st_size>100*1024*1024: raise ValueError("Mailbox exceeds 100 MiB.")
    box=mailbox.mbox(path,factory=lambda f:BytesParser(policy=policy.default).parse(f),create=False)
    try:
        result=[]
        for msg in box:
            if len(result)>=5000: raise ValueError("Mailbox exceeds 5000 messages.")
            result.append(msg)
        return result
    finally: box.close()
def text_body(msg):
    part=msg.get_body(preferencelist=("plain",))
    return part.get_content() if part else ""
def address_pairs(msg,headers=("from","to","cc","bcc","reply-to")):
    return getaddresses([str(v) for key in headers for v in msg.get_all(key,[])])
def attachments(msg):
    return [p for p in msg.walk() if p.get_content_maintype()!="multipart" and (p.get_content_disposition()=="attachment" or p.get_filename() is not None)]
def payload(part):
    if part.get_content_type()=="message/rfc822" and isinstance(part.get_payload(),list):
        return part.get_payload(0).as_bytes(policy=policy.default)
    return part.get_payload(decode=True) or b""
def save_message(path,msg):
    data=msg.as_bytes(policy=policy.SMTP)
    with Path(path).open("xb") as handle: handle.write(data)
def clean_address(value):
    if "\r" in value or "\n" in value: raise ValueError("Address cannot contain newlines.")
    display,address=parseaddr(value)
    if "@" not in address or any(c.isspace() for c in address): raise ValueError("Supply one ordinary email address.")
    return address
def draft(sender,recipient,subject,body):
    msg=EmailMessage()
    msg["From"]=clean_address(sender)
    msg["To"]=clean_address(recipient)
    msg["Subject"]=subject
    msg["Date"]=format_datetime(datetime.now(timezone.utc))
    msg["Message-ID"]=make_msgid(domain="scriptage.local")
    msg.set_content(body)
    return msg

def main():
    parser = argparse.ArgumentParser(description="Extract a saved email's plain-text body")
    parser.add_argument("--input",required=True,help="Local EML, MBOX, or body file as documented")
    parser.add_argument("--output",required=True,help="New result file or directory")
    args = parser.parse_args()
    body=text_body(message(args.input))
    if not body: raise ValueError("No plain-text body was found.")
    with Path(args.output).open("x",encoding="utf-8",newline="") as handle: handle.write(body)

if __name__ == "__main__":
    try:
        main()
    except (OSError, ValueError, KeyError, TypeError, ArithmeticError, IndexError, LookupError) as exc:
        raise SystemExit(str(exc))

Open source as plain text · Download source and sample files

How it works

All messages are read from local files; no SMTP, browser, or email-service connection is used.
Attachments are excluded by get_body; the script does not convert HTML-only messages to text.
The output begins Hello Bo and excludes the attached notes.txt.

Make it your own

--input

Select another .eml file containing a text/plain body.

Adapt the processing

Edit text_body's preference policy only if you also define safe handling for the selected content type.

Change one setting at a time, run it again on sample data, and compare the output. The customization guide walks through this process.

If something goes wrong

No plain-text body was found.

Use an email export that includes text/plain, or inspect the MIME outline.

The destination already exists.

Choose a new --output path. The script deliberately refuses to replace an existing result.

Reference & next steps

These official references explain the underlying tools. The Scriptage example and guide are original instructional content. See verification notes for what has been checked and the limits of those checks.

Copies a template for your own notes. It does not send anything.