Ticket #11928: email-recipients-tuple-fix.diff

django/core/mail.py

@@ -255 +255 @@
         Returns a list of all recipients of the email (includes direct
         addressees as well as Bcc entries).
         """
-        return self.to + self.bcc
+        return list(self.to) + list(self.bcc)
 
     def send(self, fail_silently=False):
         """Sends the email message."""