How to Parse MSG Files in Python

aspose-email-foss for Python provides a pure-Python API for reading Outlook MSG files without Microsoft Office dependencies. Load a file into a MapiMessage object to access all message data.

Step-by-Step Guide

Step 1: Install the Package

pip install aspose-email-foss

Requires Python 3.10 or later.

Step 2: Import the MapiMessage Class

from aspose.email_foss.msg.message import MapiMessage

Step 3: Load an MSG File

msg = MapiMessage.from_file("message.msg")

For lenient parsing of malformed files, pass strict=False:

msg = MapiMessage.from_file("message.msg", strict=False)

Step 4: Access Message Properties

print(f"Subject: {msg.subject()}")
print(f"Body: {msg.body()}")
print(f"HTML Body: {msg.body_html()[:200] if msg.body_html() else 'None'}")
print(f"Message Class: {msg.message_class()}")

Step 5: List Attachments

for att in msg.iter_attachments_info():
    name = att.storage_name()
    is_embedded = att.is_embedded_message()
    print(f"Attachment: {name}, embedded={is_embedded}")

Step 6: Inspect Low-Level CFB Structure

from aspose.email_foss.cfb.reader import CFBReader

reader = CFBReader.from_file("message.msg")
print(f"Directory entries: {reader.directory_entry_count()}")
for entry in reader.iter_streams():
    print(f"  Stream: {entry}")
reader.close()

Common Issues and Fixes

CFBError when loading

The file is not a valid CFB container. Verify it is an actual Outlook MSG file, not an EML.

Body is empty but HTML body has content

Some messages store content only in HTML. Check msg.body_html() when msg.body() returns None.

Validation warnings

Call msg.validation_issues() to see a tuple of compliance warnings for the loaded file.

Frequently Asked Questions (FAQ)

Can I read EML files?

Not directly. The library handles MSG (CFB) format. Convert EML content to an EmailMessage object first, then use MapiMessage.from_email_message().

Does loading read all attachment data into memory?

No. Attachment metadata is read on demand. Use iter_attachments_info() for lightweight iteration.

Is it thread-safe?

Each MapiMessage instance is independent. Concurrent reads from separate instances are safe.