Dec 24, 2025 · Dec 24, 2025 · Dec 24, 2025
diff --git a/Lib/email/_encoded_words.py b/Lib/email/_encoded_words.py

    """
    if charset == 'unknown-8bit':
        bstring = string.encode('ascii', 'surrogateescape')
        bstring = string.encode('utf-8', 'surrogateescape')
    else:
        bstring = string.encode(charset)
    if encoding is None:
diff --git a/Lib/test/test_email/test__header_value_parser.py b/Lib/test/test_email/test__header_value_parser.py
        token = parser.get_address_list(text)[0]
        self._test(token, expected, policy=policy)

    def test_encoded_word_with_undecodable_bytes(self):
        self._test(parser.get_address_list(
            ' =?utf-8?Q?=E5=AE=A2=E6=88=B6=E6=AD=A3=E8=A6=8F=E4=BA=A4=E7?='
                )[0],
            ' =?unknown-8bit?b?5a6i5oi25q2j6KaP5Lqk5w==?=\n',
            )


 if __name__ == '__main__':
    unittest.main()
diff --git a/Misc/NEWS.d/next/Library/2025-12-10-10-00-06.gh-issue-142517.fG4hbe.rst b/Misc/NEWS.d/next/Library/2025-12-10-10-00-06.gh-issue-142517.fG4hbe.rst
 The non-``compat32`` :mod:`email` policies now correctly handle refolding
 encoded words that contain bytes that can not be decoded in their specified
 character set.  Previously this resulted in an encoding exception during
 folding.
Original file line number	Diff line number	Diff line change
Expand Up		@@ -219,7 +219,7 @@ def encode(string, charset='utf-8', encoding=None, lang=''):

		"""
		if charset == 'unknown-8bit':
		bstring = string.encode('ascii', 'surrogateescape')
		bstring = string.encode('utf-8', 'surrogateescape')
		else:
		bstring = string.encode(charset)
		if encoding is None:
Expand Down
Original file line number	Diff line number	Diff line change
Expand Up		@@ -3340,5 +3340,13 @@ def test_fold_unfoldable_element_stealing_whitespace(self):
		token = parser.get_address_list(text)[0]
		self._test(token, expected, policy=policy)

		def test_encoded_word_with_undecodable_bytes(self):
		self._test(parser.get_address_list(
		' =?utf-8?Q?=E5=AE=A2=E6=88=B6=E6=AD=A3=E8=A6=8F=E4=BA=A4=E7?='
		)[0],
		' =?unknown-8bit?b?5a6i5oi25q2j6KaP5Lqk5w==?=\n',
		)


		if __name__ == '__main__':
		unittest.main()
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,4 @@
		The non-``compat32`` :mod:`email` policies now correctly handle refolding
		encoded words that contain bytes that can not be decoded in their specified
		character set. Previously this resulted in an encoding exception during
		folding.