id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
34524	"Error while sending TLS smtp email on ""self-signed certificate"" server"	Buky	nobody	"The issue appears in Django 4.2 (tested with Python 3.11 and Python 3.9). 
Correctly works with previous versions of Django: 3.2 and 4.1

Context: I use locally use the [https://proton.me/support/protonmail-bridge-install protonmail-bridge] solution that locally bind an `IMAP` and `SMTP` ports with `STARTTLS`. Then, I use in my project config the [https://docs.djangoproject.com/en/4.2/topics/email/#smtp-backend EmailBackend] to connect to the solution and send emails. 

Here is the traceback, when I try to send emails with Django 4.2:
{{{
Traceback (most recent call last):
  File ""/home/user/my-project/manage.py"", line 15, in <module>
    execute_from_command_line(sys.argv)
  File ""/home/user/.virtualenvs/env/lib/python3.11/site-packages/django/core/management/__init__.py"", line 442, in execute_from_command_line
    utility.execute()
  File ""/home/user/.virtualenvs/env/lib/python3.11/site-packages/django/core/management/__init__.py"", line 436, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File ""/home/user/.virtualenvs/env/lib/python3.11/site-packages/django/core/management/base.py"", line 412, in run_from_argv
    self.execute(*args, **cmd_options)
  File ""/home/user/.virtualenvs/env/lib/python3.11/site-packages/django/core/management/base.py"", line 458, in execute
    output = self.handle(*args, **options)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File ""/home/user/my-project/my-app/management/commands/send-mail.py"", line 62, in handle
    send_mail(f""[My subject] {options['subject']}"",
  File ""/home/user/.virtualenvs/env/lib/python3.11/site-packages/django/core/mail/__init__.py"", line 87, in send_mail
    return mail.send()
           ^^^^^^^^^^^
  File ""/home/user/.virtualenvs/env/lib/python3.11/site-packages/django/core/mail/message.py"", line 298, in send
    return self.get_connection(fail_silently).send_messages([self])
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File ""/home/user/.virtualenvs/env/lib/python3.11/site-packages/django/core/mail/backends/smtp.py"", line 127, in send_messages
    new_conn_created = self.open()
                       ^^^^^^^^^^^
  File ""/home/user/.virtualenvs/env/lib/python3.11/site-packages/django/core/mail/backends/smtp.py"", line 92, in open
    self.connection.starttls(context=self.ssl_context)
  File ""/usr/lib/python3.11/smtplib.py"", line 790, in starttls
    self.sock = context.wrap_socket(self.sock,
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File ""/usr/lib/python3.11/ssl.py"", line 517, in wrap_socket
    return self.sslsocket_class._create(
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File ""/usr/lib/python3.11/ssl.py"", line 1075, in _create
    self.do_handshake()
  File ""/usr/lib/python3.11/ssl.py"", line 1346, in do_handshake
    self._sslobj.do_handshake()
ssl.SSLCertVerificationError: [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed: self-signed certificate (_ssl.c:992)
}}}

I found [https://code.djangoproject.com/ticket/34386 another ticket] recently created ticket related to SSL issue, but the issue doesn't exactly the same and the issue doesn't precisely mention when the patch will be merged: `[4.2.x] Fixed`.

I have tried to export the TLS certificate and key of the solution and add them in my `settings.py` like:
{{{
EMAIL_SSL_CERTFILE=""/tmp/cert.pem""
EMAIL_SSL_KEYFILE=""/tmp/key.pem""
}}}
And to put them in the trust store of the system:
{{{
cp /tmp/cert.pem /usr/local/share/ca-certificates/protonmail-bridge.crt
cp /tmp/key.pem /etc/ssl/private/protonmail-bridge.key
update-ca-certificates
}}}
But both tests didn't work. 

I suppose [https://docs.python.org/3/library/ssl.html#self-signed-certificates ssl] lib need an extra argument to allow SSL context with self-signed certificate.
"	Bug	new	Core (Mail)	4.2	Normal		ssl		Unreviewed	0	0	0	0	0	0