fix: feature-detect getaddresses(strict=) so address parsing works on Python < 3.13

src/mailparser/utils.py

@@ -25,6 +25,7 @@
 import email.utils
 import functools
 import hashlib
+import inspect
 import json
 import logging
 import os
@@ -52,6 +53,30 @@
 
 log = logging.getLogger(__name__)
 
+
+def _getaddresses(fieldvalues: list[str]) -> list[tuple[str, str]]:
+    """Call ``email.utils.getaddresses`` with strict parsing when available.
+
+    The ``strict`` keyword was added to ``email.utils.getaddresses`` in
+    Python 3.13 (and backported only to later security patch releases of
+    3.9-3.12, e.g. 3.11.10).  mail-parser supports ``requires-python
+    >=3.9,<3.15``, so on an earlier patch release the keyword is absent and
+    passing it raises ``TypeError: getaddresses() got an unexpected keyword
+    argument 'strict'``.  Feature-detect it before passing ``strict=True`` so
+    older interpreters keep working (parsedmarc #808).
+    """
+    try:
+        supports_strict = (
+            "strict" in inspect.signature(email.utils.getaddresses).parameters
+        )
+    except (TypeError, ValueError):  # pragma: no cover - defensive
+        supports_strict = False
+
+    if supports_strict:
+        return email.utils.getaddresses(fieldvalues, strict=True)
+    return email.utils.getaddresses(fieldvalues)
+
+
 # ---------------------------------------------------------------------------
 # RFC 5322 address parsing — fallback for non-compliant display names
 # ---------------------------------------------------------------------------
@@ -134,7 +159,7 @@ def get_addresses(
     elif not isinstance(raw_header, str):
         raw_header = str(raw_header)
 
-    parsed = email.utils.getaddresses([raw_header], strict=True)
+    parsed = _getaddresses([raw_header])
 
     # If every result from the strict parser has an empty address — while the
     # raw header is non-empty — fall back to regex extraction so that the

tests/test_utils.py

@@ -771,6 +771,43 @@ def test_get_addresses_fallback_regex_no_matches(self):
             result = get_addresses("not an email address at all")
         self.assertEqual(result, [("", "")])
 
+    def test_get_addresses_without_strict_parameter(self):
+        """
+        Regression for parsedmarc #808: get_addresses must not pass the
+        ``strict`` keyword unconditionally to email.utils.getaddresses.
+
+        The ``strict`` parameter was added to ``email.utils.getaddresses`` in
+        Python 3.13 (and backported only to later security patch releases of
+        3.9-3.12). mail-parser targets ``requires-python >=3.9,<3.15``, so on
+        an earlier patch release (e.g. CPython 3.11.3) the call raised::
+
+            TypeError: getaddresses() got an unexpected keyword argument 'strict'
+
+        Here we simulate a pre-3.13 ``getaddresses`` (no ``strict`` parameter)
+        and assert that get_addresses parses the address instead of crashing.
+        """
+
+        import email.utils
+
+        real_getaddresses = email.utils.getaddresses
+
+        def legacy_getaddresses(fieldvalues):
+            """Mimic the pre-3.13 signature that lacks ``strict``.
+
+            Patched in as a real function (not a Mock) so that the feature
+            detection in get_addresses observes a signature without
+            ``strict`` and does not attempt to pass the keyword.
+            """
+            return real_getaddresses(fieldvalues)
+
+        with patch(
+            "mailparser.utils.email.utils.getaddresses",
+            new=legacy_getaddresses,
+        ):
+            result = get_addresses("Plain Name <plain@example.com>")
+
+        self.assertEqual(result, [("Plain Name", "plain@example.com")])
+
     def test_parse_received_sendgrid_date(self):
         """parse_received extracts SendGrid non-standard date (utils.py:389-390)"""
         received = (