Prevent an unhandled exception encoding to UTF-8 if the input has a surrogate code point

Author: JoshData

email_validator/__init__.py

@@ -368,6 +368,13 @@ def validate_email_local_part(local, allow_smtputf8=True, allow_empty_local=Fals
         # so we'll return the normalized local part in the return value.
         local = unicodedata.normalize("NFC", local)
 
+        # Try encoding to UTF-8. Failure is possible with some characters like
+        # surrogate code points.
+        try:
+            local.encode("utf8")
+        except ValueError:
+            raise EmailSyntaxError("The email address contains an invalid character.")
+
         # Flag that SMTPUTF8 will be required for deliverability.
         return {
             "local_part": local,

tests/test_main.py

@@ -283,6 +283,7 @@ def test_email_invalid_reserved_domain(email_input):
     [
         ('white space@test'),
         ('\n@test'),
+        ('\uD800@test'), # surrogate (Cs)
     ],
 )
 def test_email_unsafe_character(email_input):