SMTP regression and failure during TLS negotiation under Python 3.7.

[mentat51]

Upstream tracking bug: https://bugs.python.org/issue36094

---

from marrow.mailer import Mailer, Message

mailer = Mailer(dict(
        transport = dict(
                use = 'smtp',
                host = 'smtp.office365.com',
                port = 587,
                tls='required',
                username='username@test.com',
                password='password')))
print('connection...')
mailer.start()
print('connected')

message = Message(author="from@test.com", to="to@test.com")
message.subject = "Testing Marrow Mailer"
message.plain = "This is a test."
print('send mail')
mailer.send(message)

print('disconnect')
mailer.stop()

This works great with python 2.7, but with python 3.7 (tested on 3.7.1 and 3.7.4), I have this error :

Delivery of message <157121638590.46272.10119950910494763987@server.local> failed.
Traceback (most recent call last):
  File "C:\usr\Python37\lib\site-packages\marrow\mailer\manager\util.py", line 50, in __enter__
    transport = pool.transports.get(False)
  File "C:\usr\Python37\lib\queue.py", line 167, in get
    raise Empty
_queue.Empty

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "minimal_test.py", line 32, in <module>
    mailer.send(message)
  File "C:\usr\Python37\lib\site-packages\marrow\mailer\__init__.py", line 149, in send
    result = self.manager.deliver(message)
  File "C:\usr\Python37\lib\site-packages\marrow\mailer\manager\immediate.py", line 41, in deliver
    with self.transport() as transport:
  File "C:\usr\Python37\lib\site-packages\marrow\mailer\manager\util.py", line 57, in __enter__
    transport.startup()
  File "C:\usr\Python37\lib\site-packages\marrow\mailer\transport\smtp.py", line 50, in startup
    self.connect_to_server()
  File "C:\usr\Python37\lib\site-packages\marrow\mailer\transport\smtp.py", line 86, in connect_to_server
    connection.starttls(self.keyfile, self.certfile)
  File "C:\usr\Python37\lib\smtplib.py", line 771, in starttls
    server_hostname=self._host)
  File "C:\usr\Python37\lib\ssl.py", line 412, in wrap_socket
    session=session
  File "C:\usr\Python37\lib\ssl.py", line 846, in _create
    owner=self, session=self._session,
ValueError: server_hostname cannot be an empty string or start with a leading dot.

[iamraa]

You have to monkey-patch this method marrow.mailer.transport.smtp.SMTPTransport.connect_to_server():

# ....
    if self.tls == "ssl":
        connection = SMTP_SSL(
            host=self.host,
            local_hostname=self.local_hostname,
            keyfile=self.keyfile,
            certfile=self.certfile,
            timeout=self.timeout,
        )
    else:
        connection = SMTP(
            host=self.host, local_hostname=self.local_hostname, timeout=self.timeout
        )
# ....

[hyperknot]

Is there any other way to fix this without monkey patching? Python 3.7 is 1.5 years old, what is the proper way to use this library with it? I hope not a monkey patch.

[amcgregor]

Upstream tracking bug: https://bugs.python.org/issue36094 (my back-referencing comment therein)

Please stop submitting pull requests passing the host name to the constructor. These solutions will be immediately rejected. See also: http://xyproblem.info

[amcgregor]

See also: python/cpython#11998 — pull request correcting the issue, pending changes from code review.

[Minstel]

This error still exists. No solution except monkey-patching?

[amcgregor]

@Minstel Please see the official bug report against CPython, linked above your comment.