Use rtfparse to extract HTML message bodies from RTF containers and create mutlipart/alternative messages if both plain text and HTML are available

Also fixes #20.

README.md

@@ -1,22 +1,24 @@
 Convert Outlook .msg Files to .eml (MIME format)
 ================================================
 
-This repository contains a Python 3.6 module for
+This repository contains a Python 3.9+ module for
 reading Microsoft Outlook .msg files and converting
 them to .eml format, which is the standard MIME
 format for email messages.
 
 Install the dependencies with:
 
-    pip3.6 install -r requirements.txt
+    pip install -r requirements.txt
+
+(You may need to create and activate a Python virtual environment first.)
 
 Then either convert a single file by piping:
 
-	python3.6 outlookmsgfile.py < message.msg > message.eml
+	python outlookmsgfile.py < message.msg > message.eml
 
 Or convert a set of files:
 
-	python3.6 outlookmsgfile.py *.msg
+	python outlookmsgfile.py *.msg
 
 When passing filenames as command-line arguments, a new file with `.eml`
 appended to the filename is written out with the message in MIME format.

outlookmsgfile.py

@@ -16,6 +16,7 @@ import re
 import logging
 import os
 import sys
+import io
 
 from functools import reduce
 
@@ -23,6 +24,8 @@ import email.message, email.parser, email.policy
 from email.utils import parsedate_to_datetime, formatdate, formataddr
 
 import compoundfiles
+from rtfparse.parser import Rtf_Parser
+from rtfparse.renderers.de_encapsulate_html import De_encapsulate_HTML
 
 logger = logging.getLogger(__name__)
 
@@ -102,33 +105,57 @@ def load_message_stream(entry, is_top_level, doc):
             msg['Subject'] = props['SUBJECT']
         del props['SUBJECT']
 
-  # Add the plain-text body from the BODY field.
+  # Add a plain text body from the BODY field.
+  has_body = False
   if 'BODY' in props:
     body = props['BODY']
     if isinstance(body, str):
       msg.set_content(body, cte='quoted-printable')
     else:
       msg.set_content(body, maintype="text", subtype="plain", cte='8bit')
+    has_body = True
 
-  # Plain-text is not availabe. Use the rich text version.
-  else:
-    doc.rtf_attachments += 1
-    fn = "messagebody_{}.rtf".format(doc.rtf_attachments)
-
-    msg.set_content(
-      "<no plain text message body --- see attachment {}>".format(fn),
-      cte='quoted-printable')
-
+  # Add a HTML body from the RTF_COMPRESSED field.
+  if 'RTF_COMPRESSED' in props:
     # Decompress the value to Rich Text Format.
     import compressed_rtf
     rtf = props['RTF_COMPRESSED']
     rtf = compressed_rtf.decompress(rtf)
 
-    # Add RTF file as an attachment.
-    msg.add_attachment(
-      rtf,
-      maintype="text", subtype="rtf",
-      filename=fn)
+    # Try rtfparse to de-encapsulate HTML stored in a rich
+    # text container.
+    try:
+      rtf_blob = io.BytesIO(rtf)
+      parsed = Rtf_Parser(rtf_file=rtf_blob).parse_file()
+      html_stream = io.StringIO()
+      De_encapsulate_HTML().render(parsed, html_stream)
+      html_body = html_stream.getvalue()
+
+      if not has_body:
+        msg.set_content(html_body, subtype="html", cte='quoted-printable')
+        has_body = True
+      else:
+        msg.add_alternative(html_body, subtype="html", cte='quoted-printable')
+
+    # If that fails, just attach the RTF file to the message.
+    except:
+      doc.rtf_attachments += 1
+      fn = "messagebody_{}.rtf".format(doc.rtf_attachments)
+
+      if not has_body:
+        msg.set_content(
+          "<no plain text message body --- see attachment {}>".format(fn),
+          cte='quoted-printable')
+        has_body = True
+
+      # Add RTF file as an attachment.
+      msg.add_attachment(
+        rtf,
+        maintype="text", subtype="rtf",
+        filename=fn)
+
+  if not has_body:
+    msg.set_content("<no message body>", cte='quoted-printable')
 
   # # Copy over string values of remaining properties as headers
   # # so we don't lose any information.

requirements.txt

@@ -1,2 +1,3 @@
 compoundfiles
 compressed-rtf
+rtfparse # Python 3.9+ only

setup.py

@@ -3,6 +3,7 @@ import setuptools
 install_requires = [
     'compoundfiles',
     'compressed_rtf',
+    'rtfparse',
 ]
 
 with open("README.md", "r") as fh:
@@ -10,7 +11,7 @@ with open("README.md", "r") as fh:
 
 setuptools.setup(
     name='convert-outlook-msg-file',
-    version='0.1.0',
+    version='0.2.0',
     description='Parse Microsoft Outlook MSG files',
     author='Joshua Tauberer',
     author_email='jt@occams.info',
@@ -19,7 +20,7 @@ setuptools.setup(
     install_requires=install_requires,
     long_description=long_description,
     long_description_content_type="text/markdown",
-    python_requires='>=3.6',
+    python_requires='>=3.9',
     classifiers=[
         "Programming Language :: Python :: 3",
         "License :: OSI Approved :: MIT License",