Address review comments

Author: srinivasreddy

Lib/email/_policybase.py

@@ -15,7 +15,7 @@
     'compat32',
     ]
 
-# equivalent to pattern re.compile("[!-9;-~]+$")
+# validation regex from RFC 5322,equivalent to pattern re.compile("[!-9;-~]+$")
 valid_header_name_re = re.compile("[\041-\071\073-\176]+$")
 
 def validate_header_name(name):

Lib/test/test_email/test_email.py

@@ -742,7 +742,8 @@ def test_invalid_header_names(self):
         for policy in (email.policy.default, email.policy.compat32):
             for setter in (Message.__setitem__, Message.add_header):
                 for name, value in invalid_headers:
-                    self.do_test_invalid_header_names(policy, setter, name, value)
+                    self.do_test_invalid_header_names(
+                        policy, setter,name, value)
 
     def do_test_invalid_header_names(self, policy, setter, name, value):
         with self.subTest(policy=policy, setter=setter, name=name, value=value):

Misc/NEWS.d/next/Library/2024-12-11-17-44-36.gh-issue-127794.VwmRsp.rst

@@ -1,5 +1,4 @@
-The :meth:`email.message.Message.add_header` method now validates header
-field names according to :rfc:`RFC 5322, Section 3.6.8 <5322#section-3.6.8>`
-and raises a :exc:`ValueError` if they contain invalid characters. A similar
-argument applies if headers are added through :meth:`Message.__setitem__
-<object.__setitem__>`.
+When headers are added to :meth:`email.message.Message` objects, either through
+:meth:`email.message.Message.__setitem__` or :meth:`email.message.Message.add_header`,
+the field name is now validated according to  :rfc:`RFC 5322, Section 3.6.8 <5322#section-3.6.8>`
+and a :exc:`ValueError` is raised if the field name contains any invalid characters.