logging.handlers.SMTPHandler raises smtplib.SMTPAuthenticationError

Question

I tried this with Verizon and Gmail. Both servers denied authentication. Gmail emailed me that it denied a login attempt because the connection was not using "modern security".
I would like to know how I can use modern security with this logging handler.

logging.handlers.SMTPHandler(mailhost=('', 25),
                             fromaddr='',
                             toaddrs='',
                             subject='',
                             credentials=('username','password'),
                             secure=())

score 16 · Answer 1 · edited May 23 '17 at 12:01

For anyone coming back to this, here is how I got the SMTPHandler working with Gmail:

eh = SMTPHandler(mailhost=('smtp.gmail.com', 587),
                fromaddr=from_addr,
                toaddrs=to_addrs,
                subject=subject,
                credentials=(username, password),
                secure=())

The to_addrs variable is a string in my example. I am not sure if it can be an array or is supposed to be a space or comma-delimited string. The username variable includes the domain, like this: foo@gmail.com.

Most guides said to use port 465, here is the difference if you are curious. However, when I tried to use port 465, I got a SMTP timeout error:

Traceback (most recent call last):
File "/usr/local/lib/python3.5/smtplib.py", line 386, in getreply
  line = self.file.readline(_MAXLINE + 1)
File "/usr/local/lib/python3.5/socket.py", line 571, in readinto
  return self._sock.recv_into(b)
socket.timeout: timed out

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File "/usr/local/lib/python3.5/logging/handlers.py", line 972, in emit
  smtp = smtplib.SMTP(self.mailhost, port, timeout=self.timeout)
File "/usr/local/lib/python3.5/smtplib.py", line 251, in __init__
  (code, msg) = self.connect(host, port)
File "/usr/local/lib/python3.5/smtplib.py", line 337, in connect
  (code, msg) = self.getreply()
File "/usr/local/lib/python3.5/smtplib.py", line 390, in getreply
  + str(e))
smtplib.SMTPServerDisconnected: Connection unexpectedly closed: timed out

I switched to port 587 and Google successfully authenticated. The messages were sent.

I needed to add eh._timeout=30 to lengthen the default timeout of 5 seconds before this would work reliably. — Chris Nadovich, Jul 24 '18 at 01:31
The problem with port 465 (SSL) is the [CPython implementation](https://github.com/python/cpython/blob/e9684fac5a158be9806304a676e619857520a4dc/Lib/logging/handlers.py#L1020-L1041) always uses `smtplib.SMTP()` optionally with StartTLS instead of `smtplib.SMTP_SSL()`. — darkdragon, Jun 01 '20 at 16:41

score 7 · Accepted Answer · edited May 23 '17 at 12:24

Gmail problem:

Not addressed here. See other answers about Gmail's app authentication.

Verizon problem:

Some mail submission servers may only accept SMTPS on port 465. See What is the difference between ports 465 and 587? for elaboration. _{The Verizon mail submission server smtp.verizon.net, is one such example.}
SMTPHandler does not support SMTPS by default. You can monkeypatch the functionality.

Solution:

This forces any server to use SMTPS.
A more thorough fix would be to edit the class with a flag to enable SMTPS.

Paste the edited emit function from below, into the relevant file.

Then set it

logging.handlers.SMTPHandler.emit = emit

The default /logging/handlers.py logging.handlers.SMTPHandler.emit function

# Class SMTPHandler...
def emit(self, record):
    """
    Emit a record.

    Format the record and send it to the specified addressees.
    """
    try:
        import smtplib
        from email.utils import formatdate
        port = self.mailport
        if not port:
            port = smtplib.SMTP_PORT
        smtp = smtplib.SMTP(self.mailhost, port, timeout=self._timeout)
        msg = self.format(record)
        msg = "From: %s\r\nTo: %s\r\nSubject: %s\r\nDate: %s\r\n\r\n%s" % (
                        self.fromaddr,
                        ",".join(self.toaddrs),
                        self.getSubject(record),
                        formatdate(), msg)
        if self.username:
            if self.secure is not None:
                smtp.ehlo()
                smtp.starttls(*self.secure)
                smtp.ehlo()
            smtp.login(self.username, self.password)
        smtp.sendmail(self.fromaddr, self.toaddrs, msg)
        smtp.quit()
    except (KeyboardInterrupt, SystemExit):
        raise
    except:
        self.handleError(record)

The edited emit function

def emit(self, record):
    """
    Overwrite the logging.handlers.SMTPHandler.emit function with SMTP_SSL.
    Emit a record.
    Format the record and send it to the specified addressees.
    """
    try:
        import smtplib
        from email.utils import formatdate
        port = self.mailport
        if not port:
            port = smtplib.SMTP_PORT
        smtp = smtplib.SMTP_SSL(self.mailhost, port, timeout=self._timeout)
        msg = self.format(record)
        msg = "From: %s\r\nTo: %s\r\nSubject: %s\r\nDate: %s\r\n\r\n%s" % (self.fromaddr, ", ".join(self.toaddrs), self.getSubject(record), formatdate(), msg)
        if self.username:
            smtp.ehlo()
            smtp.login(self.username, self.password)
        smtp.sendmail(self.fromaddr, self.toaddrs, msg)
        smtp.quit()
    except (KeyboardInterrupt, SystemExit):
        raise
    except:
        self.handleError(record)

logging.handlers.SMTPHandler raises smtplib.SMTPAuthenticationError

2 Answers2