[5.0.x] Refs #34900, Refs #35361 -- Fixed SafeMIMEText.set_payload() crash on Python 3.13.

felixxm · sarahboyce · commit 2e6ae1e96a40 · 2024-04-10T18:06:34.000+02:00
Payloads with surrogates are passed to the set_payload() since python/cpython@f97f25e Backport of b231bcd from main.
diff --git a/django/core/mail/message.py b/django/core/mail/message.py
@@ -168,7 +168,8 @@ def __setitem__(self, name, val):
     def set_payload(self, payload, charset=None):
         if charset == "utf-8" and not isinstance(charset, Charset.Charset):
             has_long_lines = any(
-                len(line.encode()) > RFC5322_EMAIL_LINE_LENGTH_LIMIT
+                len(line.encode(errors="surrogateescape"))
+                > RFC5322_EMAIL_LINE_LENGTH_LIMIT
                 for line in payload.splitlines()
             )
             # Quoted-Printable encoding has the side effect of shortening long
