SMTP_SSL SSLError:[SSL:UNKNOWN_PROTOCOL]未知协议（_SSL.c:590）

Question

此问题与smtplib的SMTP_SSL连接有关。

当连接到SMTP（没有ssl）时，它正在工作。

在SMTP SSL中尝试相同的主机和端口时，出现错误。错误仅基于主机，gmail设置也可以正常工作。

请检查下面的示例，并让我知道是否需要对outlook&office365进行任何更改。

In [1]: import smtplib

In [10]: smtplib.SMTP_SSL('smtp.gmail.com', 465, timeout=100)
Out[10]: <smtplib.SMTP_SSL instance at 0x109ccaf38>

In [2]: smtplib.SMTP('smtp-mail.outlook.com', 587, timeout=100)
Out[1]: <smtplib.SMTP instance at 0x10a00bb90>

In [3]: smtplib.SMTP_SSL('smtp-mail.outlook.com', 587, timeout=100)
---------------------------------------------------------------------------
SSLError                                  Traceback (most recent call last)
<ipython-input-9-f0c5b0de4e24> in <module>()
----> 1 smtplib.SMTP_SSL('smtp-mail.outlook.com', 587, timeout=100)

/python2.7/smtplib.pyc in __init__(self, host, port, local_hostname, keyfile, certfile, timeout)
    794             self.keyfile = keyfile
    795             self.certfile = certfile
--> 796             SMTP.__init__(self, host, port, local_hostname, timeout)
    797 
    798         def _get_socket(self, host, port, timeout):

python2.7/smtplib.pyc in __init__(self, host, port, local_hostname, timeout)
    254         self.esmtp_features = {}
    255         if host:
--> 256             (code, msg) = self.connect(host, port)
    257             if code != 220:
    258                 raise SMTPConnectError(code, msg)

python2.7/smtplib.pyc in connect(self, host, port)
    314         if self.debuglevel > 0:
    315             print>>stderr, 'connect:', (host, port)
--> 316         self.sock = self._get_socket(host, port, self.timeout)
    317         (code, msg) = self.getreply()
    318         if self.debuglevel > 0:

python2.7/smtplib.pyc in _get_socket(self, host, port, timeout)
    800                 print>>stderr, 'connect:', (host, port)
    801             new_socket = socket.create_connection((host, port), timeout)
--> 802             new_socket = ssl.wrap_socket(new_socket, self.keyfile, self.certfile)
    803             self.file = SSLFakeFile(new_socket)
    804             return new_socket

python2.7/ssl.pyc in wrap_socket(sock, keyfile, certfile, server_side, cert_reqs, ssl_version, ca_certs, do_handshake_on_connect, suppress_ragged_eofs, ciphers)
    909                      do_handshake_on_connect=do_handshake_on_connect,
    910                      suppress_ragged_eofs=suppress_ragged_eofs,
--> 911                      ciphers=ciphers)
    912 
    913 # some utility functions

python2.7/ssl.pyc in __init__(self, sock, keyfile, certfile, server_side, cert_reqs, ssl_version, ca_certs, do_handshake_on_connect, family, type, proto, fileno, suppress_ragged_eofs, npn_protocols, ciphers, server_hostname, _context)
    577                         # non-blocking
    578                         raise ValueError("do_handshake_on_connect should not be specified for non-blocking sockets")
--> 579                     self.do_handshake()
    580 
    581             except (OSError, ValueError):

python2.7/ssl.pyc in do_handshake(self, block)
    806             if timeout == 0.0 and block:
    807                 self.settimeout(None)
--> 808             self._sslobj.do_handshake()
    809         finally:
    810             self.settimeout(timeout)

SSLError: [SSL: UNKNOWN_PROTOCOL] unknown protocol (_ssl.c:590)

参考URL:https://docs.python.org/2/library/smtplib.html#smtplib.SMTP_SSL