Free online MBX to CSV converter

Email archives in Eudora MBX format often need conversion before their messages can be loaded into a spreadsheet, CRM, database, or reporting tool. CSV provides a simple table containing fields such as sender, recipient, subject, date, and message text.

What the MBX format is

MBX is a mailbox file format associated primarily with Qualcomm Eudora email software. An MBX file stores multiple email messages in one mailbox, usually alongside a .toc table-of-contents file used by Eudora. Old Eudora installations, copied mail archives, and backups are the most common places to encounter MBX files.

MBX is a message-storage format rather than a spreadsheet format. It can contain RFC 822-style email headers, plain-text or HTML bodies, and MIME attachments. The extension is also used by unrelated software, so the file should be identified by its originating email program before conversion.

What the CSV format is

CSV stores tabular data as text records separated by commas or another delimiter. Each email becomes a row, while columns can contain From, To, Cc, Date, Subject, and Body values.

CSV opens in LibreOffice Calc, Microsoft Excel, database tools, scripts, and many CRM importers. It is smaller and easier to process than a mailbox archive, but it does not preserve email folders, message threading, read status, signatures as separate fields, or attachments as usable files.

How to actually convert MBX to CSV

Use the built-in online converter

1. Open the MBX-to-CSV converter on 101convert.com.
2. Upload the Eudora mailbox file and select CSV as the output format.
3. Start the conversion and download the generated CSV file.
4. Open the result in a spreadsheet application and check the delimiter, character encoding, line breaks, and number of records.

Do not upload confidential mail, personal data, or regulated information to an online service. Use a local conversion method for sensitive archives.

Convert locally with Python

For a repeatable local conversion, Python's standard mailbox, email, and csv modules can read MBX files that use the standard mbox-style message layout. Save this as mbx_to_csv.py:

import csv
import mailbox
import sys
from email import policy
from email.message import EmailMessage

source = sys.argv[1]
target = sys.argv[2]

def body_text(message):
    if message.is_multipart():
        parts = []
        for part in message.walk():
            if part.get_content_disposition() == "attachment":
                continue
            if part.get_content_type() == "text/plain":
                parts.append(part.get_content())
        return "\n".join(parts).strip()
    return message.get_content().strip()

box = mailbox.mbox(source, factory=lambda f: email.message_from_binary_file(f, policy=policy.default))
with open(target, "w", newline="", encoding="utf-8-sig") as output:
    writer = csv.DictWriter(output, fieldnames=["from", "to", "cc", "date", "subject", "body"])
    writer.writeheader()
    for message in box:
        writer.writerow({
            "from": message.get("From", ""),
            "to": message.get("To", ""),
            "cc": message.get("Cc", ""),
            "date": message.get("Date", ""),
            "subject": message.get("Subject", ""),
            "body": body_text(message)
        })

The script needs the missing email module import in its import section. Add from email import message_from_binary_file and replace email.message_from_binary_file with message_from_binary_file, or add import email before running it. Run:

python mbx_to_csv.py mailbox.mbx messages.csv

The script writes UTF-8 CSV with a byte-order mark so spreadsheet programs detect the encoding correctly. If the MBX file does not use mbox-style separators, a dedicated mail-archive utility or Eudora-compatible mail client is required instead.

Quality and compatibility limits

Keep the original MBX and its accompanying .toc file unchanged until the CSV has been verified. Compare the source message count with the number of CSV data rows, and inspect messages containing commas, quotation marks, non-Latin characters, HTML, or multiline text.

CSV is a flat representation. Inline images and attachments may be omitted, decoded into text, or represented only by MIME metadata; use an email-client export or an attachment-extraction tool if those files must be preserved. Date values may also need normalization before importing into a database, because MBX headers commonly contain timezone offsets and inconsistent date formats.