[4.2.x] Refs #34118, Refs #34504 -- Added backward incompatibility note about EmailBackend.ssl_context.

Follow up to 2848e5d0ce.
Backport of 5a6d4d3bfd from main

docs/releases/4.2.txt

@@ -467,6 +467,12 @@ Miscellaneous
 
 * Support for ``PROJ`` < 5 is removed.
 
+* :class:`~django.core.mail.backends.smtp.EmailBackend` now verifies a
+  :py:attr:`hostname <ssl.SSLContext.check_hostname>` and
+  :py:attr:`certificates <ssl.SSLContext.verify_mode>`. If you need the
+  previous behavior that is less restrictive and not recommended, subclass
+  ``EmailBackend`` and override the ``ssl_context`` property.
+
 .. _deprecated-features-4.2:
 
 Features deprecated in 4.2