text: #! /usr/bin/env python3
  
  '''SMTP/ESMTP client class.
  
  This should follow RFC 821 (SMTP), RFC 1869 (ESMTP), RFC 2554 (SMTP
  Authentication) and RFC 2487 (Secure SMTP over TLS).
  
  Notes:
  
  Please remember, when doing ESMTP, that the names of the SMTP service
  extensions are NOT the same thing as the option keywords for the RCPT
  and MAIL commands!
  
  Example:
  
    >>> import smtplib
    >>> s=smtplib.SMTP("localhost")
    >>> print(s.help())
    This is Sendmail version 8.8.4
    Topics:
        HELO    EHLO    MAIL    RCPT    DATA
        RSET    NOOP    QUIT    HELP    VRFY
        EXPN    VERB    ETRN    DSN
    For more info use "HELP <topic>".
    To report bugs in the implementation send email to
        sendmail-bugs@sendmail.org.
    For local information send email to Postmaster at your site.
    End of HELP info
    >>> s.putcmd("vrfy","someone@here")
    >>> s.getreply()
    (250, "Somebody OverHere <somebody@here.my.org>")
    >>> s.quit()
  '''
  
  # Author: The Dragon De Monsyne <dragondm@integral.org>
  # ESMTP support, test code and doc fixes added by
  #     Eric S. Raymond <esr@thyrsus.com>
  # Better RFC 821 compliance (MAIL and RCPT, and CRLF in data)
  #     by Carey Evans <c.evans@clear.net.nz>, for picky mail servers.
  # RFC 2554 (authentication) support by Gerhard Haering <gerhard@bigfoot.de>.
  #
  # This was modified from the Python 1.5 library HTTP lib.
  
  import socket
  import io
  import re
  import email.utils
  import email.message
  import email.generator
  import base64
  import hmac
  import copy
  from email.base64mime import body_encode as encode_base64
  from sys import stderr
  
  __all__ = ["SMTPException", "SMTPServerDisconnected", "SMTPResponseException",
             "SMTPSenderRefused", "SMTPRecipientsRefused", "SMTPDataError",
             "SMTPConnectError", "SMTPHeloError", "SMTPAuthenticationError",
             "quoteaddr", "quotedata", "SMTP"]
  
  SMTP_PORT = 25
  SMTP_SSL_PORT = 465
  CRLF = "\r\n"
  bCRLF = b"\r\n"
  _MAXLINE = 8192 # more than 8 times larger than RFC 821, 4.5.3
  
  OLDSTYLE_AUTH = re.compile(r"auth=(.*)", re.I)
  
  # Exception classes used by this module.
  class SMTPException(Exception):
      """Base class for all exceptions raised by this module."""
  
  class SMTPServerDisconnected(SMTPException):
      """Not connected to any SMTP server.
  
      This exception is raised when the server unexpectedly disconnects,
      or when an attempt is made to use the SMTP instance before
      connecting it to a server.
      """
  
  class SMTPResponseException(SMTPException):
      """Base class for all exceptions that include an SMTP error code.
  
      These exceptions are generated in some instances when the SMTP
      server returns an error code.  The error code is stored in the
      `smtp_code' attribute of the error, and the `smtp_error' attribute
      is set to the error message.
      """
  
      def __init__(self, code, msg):
          self.smtp_code = code
          self.smtp_error = msg
          self.args = (code, msg)
  
  class SMTPSenderRefused(SMTPResponseException):
      """Sender address refused.
  
      In addition to the attributes set by on all SMTPResponseException
      exceptions, this sets `sender' to the string that the SMTP refused.
      """
  
      def __init__(self, code, msg, sender):
          self.smtp_code = code
          self.smtp_error = msg
          self.sender = sender
          self.args = (code, msg, sender)
  
  class SMTPRecipientsRefused(SMTPException):
      """All recipient addresses refused.
  
      The errors for each recipient are accessible through the attribute
      'recipients', which is a dictionary of exactly the same sort as
      SMTP.sendmail() returns.
      """
  
      def __init__(self, recipients):
          self.recipients = recipients
          self.args = (recipients,)
  
  
  class SMTPDataError(SMTPResponseException):
      """The SMTP server didn't accept the data."""
  
  class SMTPConnectError(SMTPResponseException):
      """Error during connection establishment."""
  
  class SMTPHeloError(SMTPResponseException):
      """The server refused our HELO reply."""
  
  class SMTPAuthenticationError(SMTPResponseException):
      """Authentication error.
  
      Most probably the server didn't accept the username/password
      combination provided.
      """
  
  def quoteaddr(addrstring):
      """Quote a subset of the email addresses defined by RFC 821.
  
      Should be able to handle anything email.utils.parseaddr can handle.
      """
      displayname, addr = email.utils.parseaddr(addrstring)
      if (displayname, addr) == ('', ''):
          # parseaddr couldn't parse it, use it as is and hope for the best.
          if addrstring.strip().startswith('<'):
              return addrstring
          return "<%s>" % addrstring
      return "<%s>" % addr
  
  def _addr_only(addrstring):
      displayname, addr = email.utils.parseaddr(addrstring)
      if (displayname, addr) == ('', ''):
          # parseaddr couldn't parse it, so use it as is.
          return addrstring
      return addr
  
  # Legacy method kept for backward compatibility.
  def quotedata(data):
      """Quote data for email.
  
      Double leading '.', and change Unix newline '\\n', or Mac '\\r' into
      Internet CRLF end-of-line.
      """
      return re.sub(r'(?m)^\.', '..',
          re.sub(r'(?:\r\n|\n|\r(?!\n))', CRLF, data))
  
  def _quote_periods(bindata):
      return re.sub(br'(?m)^\.', b'..', bindata)
  
  def _fix_eols(data):
      return  re.sub(r'(?:\r\n|\n|\r(?!\n))', CRLF, data)
  
  try:
      import ssl
  except ImportError:
      _have_ssl = False
  else:
      _have_ssl = True
  
  
  class SMTP:
      """This class manages a connection to an SMTP or ESMTP server.
      SMTP Objects:
          SMTP objects have the following attributes:
              helo_resp
                  This is the message given by the server in response to the
                  most recent HELO command.
  
              ehlo_resp
                  This is the message given by the server in response to the
                  most recent EHLO command. This is usually multiline.
  
              does_esmtp
                  This is a True value _after you do an EHLO command_, if the
                  server supports ESMTP.
  
              esmtp_features
                  This is a dictionary, which, if the server supports ESMTP,
                  will _after you do an EHLO command_, contain the names of the
                  SMTP service extensions this server supports, and their
                  parameters (if any).
  
                  Note, all extension names are mapped to lower case in the
                  dictionary.
  
          See each method's docstrings for details.  In general, there is a
          method of the same name to perform each SMTP command.  There is also a
          method called 'sendmail' that will do an entire mail transaction.
          """
      debuglevel = 0
      file = None
      helo_resp = None
      ehlo_msg = "ehlo"
      ehlo_resp = None
      does_esmtp = 0
      default_port = SMTP_PORT
  
      def __init__(self, host='', port=0, local_hostname=None,
                   timeout=socket._GLOBAL_DEFAULT_TIMEOUT,
                   source_address=None):
          """Initialize a new instance.
  
          If specified, `host' is the name of the remote host to which to
          connect.  If specified, `port' specifies the port to which to connect.
          By default, smtplib.SMTP_PORT is used.  If a host is specified the
          connect method is called, and if it returns anything other than a
          success code an SMTPConnectError is raised.  If specified,
          `local_hostname` is used as the FQDN of the local host in the HELO/EHLO
          command.  Otherwise, the local hostname is found using
          socket.getfqdn(). The `source_address` parameter takes a 2-tuple (host,
          port) for the socket to bind to as its source address before
          connecting. If the host is '' and port is 0, the OS default behavior
          will be used.
  
          """
          self.timeout = timeout
          self.esmtp_features = {}
          self.source_address = source_address
  
          if host:
              (code, msg) = self.connect(host, port)
              if code != 220:
                  raise SMTPConnectError(code, msg)
          if local_hostname is not None:
              self.local_hostname = local_hostname
          else:
              # RFC 2821 says we should use the fqdn in the EHLO/HELO verb, and
              # if that can't be calculated, that we should use a domain literal
              # instead (essentially an encoded IP address like [A.B.C.D]).
              fqdn = socket.getfqdn()
              if '.' in fqdn:
                  self.local_hostname = fqdn
              else:
                  # We can't find an fqdn hostname, so use a domain literal
                  addr = '127.0.0.1'
                  try:
                      addr = socket.gethostbyname(socket.gethostname())
                  except socket.gaierror:
                      pass
                  self.local_hostname = '[%s]' % addr
  
      def __enter__(self):
          return self
  
      def __exit__(self, *args):
          try:
              code, message = self.docmd("QUIT")
              if code != 221:
                  raise SMTPResponseException(code, message)
          except SMTPServerDisconnected:
              pass
          finally:
              self.close()
  
      def set_debuglevel(self, debuglevel):
          """Set the debug output level.
  
          A non-false value results in debug messages for connection and for all
          messages sent to and received from the server.
  
          """
          self.debuglevel = debuglevel
  
      def _get_socket(self, host, port, timeout):
          # This makes it simpler for SMTP_SSL to use the SMTP connect code
          # and just alter the socket connection bit.
          if self.debuglevel > 0:
              print('connect: to', (host, port), self.source_address,
                                   file=stderr)
          return socket.create_connection((host, port), timeout,
                                          self.source_address)
  
      def connect(self, host='localhost', port=0, source_address=None):
          """Connect to a host on a given port.
  
          If the hostname ends with a colon (`:') followed by a number, and
          there is no port specified, that suffix will be stripped off and the
          number interpreted as the port number to use.
  
          Note: This method is automatically invoked by __init__, if a host is
          specified during instantiation.
  
          """
  
          if source_address:
              self.source_address = source_address
  
          if not port and (host.find(':') == host.rfind(':')):
              i = host.rfind(':')
              if i >= 0:
                  host, port = host[:i], host[i + 1:]
                  try:
                      port = int(port)
                  except ValueError:
                      raise socket.error("nonnumeric port")
          if not port:
              port = self.default_port
          if self.debuglevel > 0:
              print('connect:', (host, port), file=stderr)
          self.sock = self._get_socket(host, port, self.timeout)
          self.file = None
          (code, msg) = self.getreply()
          if self.debuglevel > 0:
              print("connect:", msg, file=stderr)
          return (code, msg)
  
      def send(self, s):
          """Send `s' to the server."""
          if self.debuglevel > 0:
              print('send:', repr(s), file=stderr)
          if hasattr(self, 'sock') and self.sock:
              if isinstance(s, str):
                  s = s.encode("ascii")
              try:
                  self.sock.sendall(s)
              except socket.error:
                  self.close()
                  raise SMTPServerDisconnected('Server not connected')
          else:
              raise SMTPServerDisconnected('please run connect() first')
  
      def putcmd(self, cmd, args=""):
          """Send a command to the server."""
          if args == "":
              str = '%s%s' % (cmd, CRLF)
          else:
              str = '%s %s%s' % (cmd, args, CRLF)
          self.send(str)
  
      def getreply(self):
          """Get a reply from the server.
  
          Returns a tuple consisting of:
  
            - server response code (e.g. '250', or such, if all goes well)
              Note: returns -1 if it can't read response code.
  
            - server response string corresponding to response code (multiline
              responses are converted to a single, multiline string).
  
          Raises SMTPServerDisconnected if end-of-file is reached.
          """
          resp = []
          if self.file is None:
              self.file = self.sock.makefile('rb')
          while 1:
              try:
                  line = self.file.readline(_MAXLINE + 1)
              except socket.error as e:
                  self.close()
                  raise SMTPServerDisconnected("Connection unexpectedly closed: "
                                               + str(e))
              if not line:
                  self.close()
                  raise SMTPServerDisconnected("Connection unexpectedly closed")
              if self.debuglevel > 0:
                  print('reply:', repr(line), file=stderr)
              if len(line) > _MAXLINE:
                  raise SMTPResponseException(500, "Line too long.")
              resp.append(line[4:].strip(b' \t\r\n'))
              code = line[:3]
              # Check that the error code is syntactically correct.
              # Don't attempt to read a continuation line if it is broken.
              try:
                  errcode = int(code)
              except ValueError:
                  errcode = -1
                  break
              # Check if multiline response.
              if line[3:4] != b"-":
                  break
  
          errmsg = b"\n".join(resp)
          if self.debuglevel > 0:
              print('reply: retcode (%s); Msg: %s' % (errcode, errmsg),
                                                      file=stderr)
          return errcode, errmsg
  
      def docmd(self, cmd, args=""):
          """Send a command, and return its response code."""
          self.putcmd(cmd, args)
          return self.getreply()
  
      # std smtp commands
      def helo(self, name=''):
          """SMTP 'helo' command.
          Hostname to send for this command defaults to the FQDN of the local
          host.
          """
          self.putcmd("helo", name or self.local_hostname)
          (code, msg) = self.getreply()
          self.helo_resp = msg
          return (code, msg)
  
      def ehlo(self, name=''):
          """ SMTP 'ehlo' command.
          Hostname to send for this command defaults to the FQDN of the local
          host.
          """
          self.esmtp_features = {}
          self.putcmd(self.ehlo_msg, name or self.local_hostname)
          (code, msg) = self.getreply()
          # According to RFC1869 some (badly written)
          # MTA's will disconnect on an ehlo. Toss an exception if
          # that happens -ddm
          if code == -1 and len(msg) == 0:
              self.close()
              raise SMTPServerDisconnected("Server not connected")
          self.ehlo_resp = msg
          if code != 250:
              return (code, msg)
          self.does_esmtp = 1
          #parse the ehlo response -ddm
          assert isinstance(self.ehlo_resp, bytes), repr(self.ehlo_resp)
          resp = self.ehlo_resp.decode("latin-1").split('\n')
          del resp[0]
          for each in resp:
              # To be able to communicate with as many SMTP servers as possible,
              # we have to take the old-style auth advertisement into account,
              # because:
              # 1) Else our SMTP feature parser gets confused.
              # 2) There are some servers that only advertise the auth methods we
              #    support using the old style.
              auth_match = OLDSTYLE_AUTH.match(each)
              if auth_match:
                  # This doesn't remove duplicates, but that's no problem
                  self.esmtp_features["auth"] = self.esmtp_features.get("auth", "") \
                          + " " + auth_match.groups(0)[0]
                  continue
  
              # RFC 1869 requires a space between ehlo keyword and parameters.
              # It's actually stricter, in that only spaces are allowed between
              # parameters, but were not going to check for that here.  Note
              # that the space isn't present if there are no parameters.
              m = re.match(r'(?P<feature>[A-Za-z0-9][A-Za-z0-9\-]*) ?', each)
              if m:
                  feature = m.group("feature").lower()
                  params = m.string[m.end("feature"):].strip()
                  if feature == "auth":
                      self.esmtp_features[feature] = self.esmtp_features.get(feature, "") \
                              + " " + params
                  else:
                      self.esmtp_features[feature] = params
          return (code, msg)
  
      def has_extn(self, opt):
          """Does the server support a given SMTP service extension?"""
          return opt.lower() in self.esmtp_features
  
      def help(self, args=''):
          """SMTP 'help' command.
          Returns help text from server."""
          self.putcmd("help", args)
          return self.getreply()[1]
  
      def rset(self):
          """SMTP 'rset' command -- resets session."""
          return self.docmd("rset")
  
      def noop(self):
          """SMTP 'noop' command -- doesn't do anything :>"""
          return self.docmd("noop")
  
      def mail(self, sender, options=[]):
          """SMTP 'mail' command -- begins mail xfer session."""
          optionlist = ''
          if options and self.does_esmtp:
              optionlist = ' ' + ' '.join(options)
          self.putcmd("mail", "FROM:%s%s" % (quoteaddr(sender), optionlist))
          return self.getreply()
  
      def rcpt(self, recip, options=[]):
          """SMTP 'rcpt' command -- indicates 1 recipient for this mail."""
          optionlist = ''
          if options and self.does_esmtp:
              optionlist = ' ' + ' '.join(options)
          self.putcmd("rcpt", "TO:%s%s" % (quoteaddr(recip), optionlist))
          return self.getreply()
  
      def data(self, msg):
          """SMTP 'DATA' command -- sends message data to server.
  
          Automatically quotes lines beginning with a period per rfc821.
          Raises SMTPDataError if there is an unexpected reply to the
          DATA command; the return value from this method is the final
          response code received when the all data is sent.  If msg
          is a string, lone '\r' and '\n' characters are converted to
          '\r\n' characters.  If msg is bytes, it is transmitted as is.
          """
          self.putcmd("data")
          (code, repl) = self.getreply()
          if self.debuglevel > 0:
              print("data:", (code, repl), file=stderr)
          if code != 354:
              raise SMTPDataError(code, repl)
          else:
              if isinstance(msg, str):
                  msg = _fix_eols(msg).encode('ascii')
              q = _quote_periods(msg)
              if q[-2:] != bCRLF:
                  q = q + bCRLF
              q = q + b"." + bCRLF
              self.send(q)
              (code, msg) = self.getreply()
              if self.debuglevel > 0:
                  print("data:", (code, msg), file=stderr)
              return (code, msg)
  
      def verify(self, address):
          """SMTP 'verify' command -- checks for address validity."""
          self.putcmd("vrfy", _addr_only(address))
          return self.getreply()
      # a.k.a.
      vrfy = verify
  
      def expn(self, address):
          """SMTP 'expn' command -- expands a mailing list."""
          self.putcmd("expn", _addr_only(address))
          return self.getreply()
  
      # some useful methods
  
      def ehlo_or_helo_if_needed(self):
          """Call self.ehlo() and/or self.helo() if needed.
  
          If there has been no previous EHLO or HELO command this session, this
          method tries ESMTP EHLO first.
  
          This method may raise the following exceptions:
  
           SMTPHeloError            The server didn't reply properly to
                                    the helo greeting.
          """
          if self.helo_resp is None and self.ehlo_resp is None:
              if not (200 <= self.ehlo()[0] <= 299):
                  (code, resp) = self.helo()
                  if not (200 <= code <= 299):
                      raise SMTPHeloError(code, resp)
  
      def login(self, user, password):
          """Log in on an SMTP server that requires authentication.
  
          The arguments are:
              - user:     The user name to authenticate with.
              - password: The password for the authentication.
  
          If there has been no previous EHLO or HELO command this session, this
          method tries ESMTP EHLO first.
  
          This method will return normally if the authentication was successful.
  
          This method may raise the following exceptions:
  
           SMTPHeloError            The server didn't reply properly to
                                    the helo greeting.
           SMTPAuthenticationError  The server didn't accept the username/
                                    password combination.
           SMTPException            No suitable authentication method was
                                    found.
          """
  
          def encode_cram_md5(challenge, user, password):
              challenge = base64.decodebytes(challenge)
              response = user + " " + hmac.HMAC(password.encode('ascii'),
                                                challenge).hexdigest()
              return encode_base64(response.encode('ascii'), eol='')
  
          def encode_plain(user, password):
              s = "\0%s\0%s" % (user, password)
              return encode_base64(s.encode('ascii'), eol='')
  
          AUTH_PLAIN = "PLAIN"
          AUTH_CRAM_MD5 = "CRAM-MD5"
          AUTH_LOGIN = "LOGIN"
  
          self.ehlo_or_helo_if_needed()
  
          if not self.has_extn("auth"):
              raise SMTPException("SMTP AUTH extension not supported by server.")
  
          # Authentication methods the server claims to support
          advertised_authlist = self.esmtp_features["auth"].split()
  
          # List of authentication methods we support: from preferred to
          # less preferred methods. Except for the purpose of testing the weaker
          # ones, we prefer stronger methods like CRAM-MD5:
          preferred_auths = [AUTH_CRAM_MD5, AUTH_PLAIN, AUTH_LOGIN]
  
          # We try the authentication methods the server advertises, but only the
          # ones *we* support. And in our preferred order.
          authlist = [auth for auth in preferred_auths if auth in advertised_authlist]
          if not authlist:
              raise SMTPException("No suitable authentication method found.")
  
          # Some servers advertise authentication methods they don't really
          # support, so if authentication fails, we continue until we've tried
          # all methods.
          for authmethod in authlist:
              if authmethod == AUTH_CRAM_MD5:
                  (code, resp) = self.docmd("AUTH", AUTH_CRAM_MD5)
                  if code == 334:
                      (code, resp) = self.docmd(encode_cram_md5(resp, user, password))
              elif authmethod == AUTH_PLAIN:
                  (code, resp) = self.docmd("AUTH",
                      AUTH_PLAIN + " " + encode_plain(user, password))
              elif authmethod == AUTH_LOGIN:
                  (code, resp) = self.docmd("AUTH",
                      "%s %s" % (AUTH_LOGIN, encode_base64(user.encode('ascii'), eol='')))
                  if code == 334:
                      (code, resp) = self.docmd(encode_base64(password.encode('ascii'), eol=''))
  
              # 235 == 'Authentication successful'
              # 503 == 'Error: already authenticated'
              if code in (235, 503):
                  return (code, resp)
  
          # We could not login sucessfully. Return result of last attempt.
          raise SMTPAuthenticationError(code, resp)
  
      def starttls(self, keyfile=None, certfile=None, context=None):
          """Puts the connection to the SMTP server into TLS mode.
  
          If there has been no previous EHLO or HELO command this session, this
          method tries ESMTP EHLO first.
  
          If the server supports TLS, this will encrypt the rest of the SMTP
          session. If you provide the keyfile and certfile parameters,
          the identity of the SMTP server and client can be checked. This,
          however, depends on whether the socket module really checks the
          certificates.
  
          This method may raise the following exceptions:
  
           SMTPHeloError            The server didn't reply properly to
                                    the helo greeting.
          """
          self.ehlo_or_helo_if_needed()
          if not self.has_extn("starttls"):
              raise SMTPException("STARTTLS extension not supported by server.")
          (resp, reply) = self.docmd("STARTTLS")
          if resp == 220:
              if not _have_ssl:
                  raise RuntimeError("No SSL support included in this Python")
              if context is not None and keyfile is not None:
                  raise ValueError("context and keyfile arguments are mutually "
                                   "exclusive")
              if context is not None and certfile is not None:
                  raise ValueError("context and certfile arguments are mutually "
                                   "exclusive")
              if context is not None:
                  self.sock = context.wrap_socket(self.sock)
              else:
                  self.sock = ssl.wrap_socket(self.sock, keyfile, certfile)
              self.file = None
              # RFC 3207:
              # The client MUST discard any knowledge obtained from
              # the server, such as the list of SMTP service extensions,
              # which was not obtained from the TLS negotiation itself.
              self.helo_resp = None
              self.ehlo_resp = None
              self.esmtp_features = {}
              self.does_esmtp = 0
          else:
              # RFC 3207:
              # 501 Syntax error (no parameters allowed)
              # 454 TLS not available due to temporary reason
              raise SMTPResponseException(resp, reply)
          return (resp, reply)
  
      def sendmail(self, from_addr, to_addrs, msg, mail_options=[],
                   rcpt_options=[]):
          """This command performs an entire mail transaction.
  
          The arguments are:
              - from_addr    : The address sending this mail.
              - to_addrs     : A list of addresses to send this mail to.  A bare
                               string will be treated as a list with 1 address.
              - msg          : The message to send.
              - mail_options : List of ESMTP options (such as 8bitmime) for the
                               mail command.
              - rcpt_options : List of ESMTP options (such as DSN commands) for
                               all the rcpt commands.
  
          msg may be a string containing characters in the ASCII range, or a byte
          string.  A string is encoded to bytes using the ascii codec, and lone
          \\r and \\n characters are converted to \\r\\n characters.
  
          If there has been no previous EHLO or HELO command this session, this
          method tries ESMTP EHLO first.  If the server does ESMTP, message size
          and each of the specified options will be passed to it.  If EHLO
          fails, HELO will be tried and ESMTP options suppressed.
  
          This method will return normally if the mail is accepted for at least
          one recipient.  It returns a dictionary, with one entry for each
          recipient that was refused.  Each entry contains a tuple of the SMTP
          error code and the accompanying error message sent by the server.
  
          This method may raise the following exceptions:
  
           SMTPHeloError          The server didn't reply properly to
                                  the helo greeting.
           SMTPRecipientsRefused  The server rejected ALL recipients
                                  (no mail was sent).
           SMTPSenderRefused      The server didn't accept the from_addr.
           SMTPDataError          The server replied with an unexpected
                                  error code (other than a refusal of
                                  a recipient).
  
          Note: the connection will be open even after an exception is raised.
  
          Example:
  
           >>> import smtplib
           >>> s=smtplib.SMTP("localhost")
           >>> tolist=["one@one.org","two@two.org","three@three.org","four@four.org"]
           >>> msg = '''\\
           ... From: Me@my.org
           ... Subject: testin'...
           ...
           ... This is a test '''
           >>> s.sendmail("me@my.org",tolist,msg)
           { "three@three.org" : ( 550 ,"User unknown" ) }
           >>> s.quit()
  
          In the above example, the message was accepted for delivery to three
          of the four addresses, and one was rejected, with the error code
          550.  If all addresses are accepted, then the method will return an
          empty dictionary.
  
          """
          self.ehlo_or_helo_if_needed()
          esmtp_opts = []
          if isinstance(msg, str):
              msg = _fix_eols(msg).encode('ascii')
          if self.does_esmtp:
              # Hmmm? what's this? -ddm
              # self.esmtp_features['7bit']=""
              if self.has_extn('size'):
                  esmtp_opts.append("size=%d" % len(msg))
              for option in mail_options:
                  esmtp_opts.append(option)
          (code, resp) = self.mail(from_addr, esmtp_opts)
          if code != 250:
              if code == 421:
                  self.close()
              else:
                  self.rset()
              raise SMTPSenderRefused(code, resp, from_addr)
          senderrs = {}
          if isinstance(to_addrs, str):
              to_addrs = [to_addrs]
          for each in to_addrs:
              (code, resp) = self.rcpt(each, rcpt_options)
              if (code != 250) and (code != 251):
                  senderrs[each] = (code, resp)
              if code == 421:
                  self.close()
                  raise SMTPRecipientsRefused(senderrs)
          if len(senderrs) == len(to_addrs):
              # the server refused all our recipients
              self.rset()
              raise SMTPRecipientsRefused(senderrs)
          (code, resp) = self.data(msg)
          if code != 250:
              if code == 421:
                  self.close()
              else:
                  self.rset()
              raise SMTPDataError(code, resp)
          #if we got here then somebody got our mail
          return senderrs
  
      def send_message(self, msg, from_addr=None, to_addrs=None,
                  mail_options=[], rcpt_options={}):
          """Converts message to a bytestring and passes it to sendmail.
  
          The arguments are as for sendmail, except that msg is an
          email.message.Message object.  If from_addr is None or to_addrs is
          None, these arguments are taken from the headers of the Message as
          described in RFC 2822 (a ValueError is raised if there is more than
          one set of 'Resent-' headers).  Regardless of the values of from_addr and
          to_addr, any Bcc field (or Resent-Bcc field, when the Message is a
          resent) of the Message object won't be transmitted.  The Message
          object is then serialized using email.generator.BytesGenerator and
          sendmail is called to transmit the message.
  
          """
          # 'Resent-Date' is a mandatory field if the Message is resent (RFC 2822
          # Section 3.6.6). In such a case, we use the 'Resent-*' fields.  However,
          # if there is more than one 'Resent-' block there's no way to
          # unambiguously determine which one is the most recent in all cases,
          # so rather than guess we raise a ValueError in that case.
          #
          # TODO implement heuristics to guess the correct Resent-* block with an
          # option allowing the user to enable the heuristics.  (It should be
          # possible to guess correctly almost all of the time.)
  
          resent = msg.get_all('Resent-Date')
          if resent is None:
              header_prefix = ''
          elif len(resent) == 1:
              header_prefix = 'Resent-'
          else:
              raise ValueError("message has more than one 'Resent-' header block")
          if from_addr is None:
              # Prefer the sender field per RFC 2822:3.6.2.
              from_addr = (msg[header_prefix + 'Sender']
                             if (header_prefix + 'Sender') in msg
                             else msg[header_prefix + 'From'])
          if to_addrs is None:
              addr_fields = [f for f in (msg[header_prefix + 'To'],
                                         msg[header_prefix + 'Bcc'],
                                         msg[header_prefix + 'Cc']) if f is not None]
              to_addrs = [a[1] for a in email.utils.getaddresses(addr_fields)]
          # Make a local copy so we can delete the bcc headers.
          msg_copy = copy.copy(msg)
          del msg_copy['Bcc']
          del msg_copy['Resent-Bcc']
          with io.BytesIO() as bytesmsg:
              g = email.generator.BytesGenerator(bytesmsg)
              g.flatten(msg_copy, linesep='\r\n')
              flatmsg = bytesmsg.getvalue()
          return self.sendmail(from_addr, to_addrs, flatmsg, mail_options,
                               rcpt_options)
  
      def close(self):
          """Close the connection to the SMTP server."""
          if self.file:
              self.file.close()
          self.file = None
          if self.sock:
              self.sock.close()
          self.sock = None
  
      def quit(self):
          """Terminate the SMTP session."""
          res = self.docmd("quit")
          self.close()
          return res
  
  if _have_ssl:
  
      class SMTP_SSL(SMTP):
          """ This is a subclass derived from SMTP that connects over an SSL
          encrypted socket (to use this class you need a socket module that was
          compiled with SSL support). If host is not specified, '' (the local
          host) is used. If port is omitted, the standard SMTP-over-SSL port
          (465) is used.  local_hostname and source_address have the same meaning
          as they do in the SMTP class.  keyfile and certfile are also optional -
          they can contain a PEM formatted private key and certificate chain file
          for the SSL connection. context also optional, can contain a
          SSLContext, and is an alternative to keyfile and certfile; If it is
          specified both keyfile and certfile must be None.
  
          """
  
          default_port = SMTP_SSL_PORT
  
          def __init__(self, host='', port=0, local_hostname=None,
                       keyfile=None, certfile=None,
                       timeout=socket._GLOBAL_DEFAULT_TIMEOUT,
                       source_address=None, context=None):
              if context is not None and keyfile is not None:
                  raise ValueError("context and keyfile arguments are mutually "
                                   "exclusive")
              if context is not None and certfile is not None:
                  raise ValueError("context and certfile arguments are mutually "
                                   "exclusive")
              self.keyfile = keyfile
              self.certfile = certfile
              self.context = context
              SMTP.__init__(self, host, port, local_hostname, timeout,
                      source_address)
  
          def _get_socket(self, host, port, timeout):
              if self.debuglevel > 0:
                  print('connect:', (host, port), file=stderr)
              new_socket = socket.create_connection((host, port), timeout,
                      self.source_address)
              if self.context is not None:
                  new_socket = self.context.wrap_socket(new_socket)
              else:
                  new_socket = ssl.wrap_socket(new_socket, self.keyfile, self.certfile)
              return new_socket
  
      __all__.append("SMTP_SSL")
  
  #
  # LMTP extension
  #
  LMTP_PORT = 2003
  
  class LMTP(SMTP):
      """LMTP - Local Mail Transfer Protocol
  
      The LMTP protocol, which is very similar to ESMTP, is heavily based
      on the standard SMTP client. It's common to use Unix sockets for
      LMTP, so our connect() method must support that as well as a regular
      host:port server.  local_hostname and source_address have the same
      meaning as they do in the SMTP class.  To specify a Unix socket,
      you must use an absolute path as the host, starting with a '/'.
  
      Authentication is supported, using the regular SMTP mechanism. When
      using a Unix socket, LMTP generally don't support or require any
      authentication, but your mileage might vary."""
  
      ehlo_msg = "lhlo"
  
      def __init__(self, host='', port=LMTP_PORT, local_hostname=None,
              source_address=None):
          """Initialize a new instance."""
          SMTP.__init__(self, host, port, local_hostname=local_hostname,
                        source_address=source_address)
  
      def connect(self, host='localhost', port=0, source_address=None):
          """Connect to the LMTP daemon, on either a Unix or a TCP socket."""
          if host[0] != '/':
              return SMTP.connect(self, host, port, source_address=source_address)
  
          # Handle Unix-domain sockets.
          try:
              self.sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
              self.file = None
              self.sock.connect(host)
          except socket.error:
              if self.debuglevel > 0:
                  print('connect fail:', host, file=stderr)
              if self.sock:
                  self.sock.close()
              self.sock = None
              raise
          (code, msg) = self.getreply()
          if self.debuglevel > 0:
              print('connect:', msg, file=stderr)
          return (code, msg)
  
  
  # Test the sendmail method, which tests most of the others.
  # Note: This always sends to localhost.
  if __name__ == '__main__':
      import sys
  
      def prompt(prompt):
          sys.stdout.write(prompt + ": ")
          sys.stdout.flush()
          return sys.stdin.readline().strip()
  
      fromaddr = prompt("From")
      toaddrs = prompt("To").split(',')
      print("Enter message, end with ^D:")
      msg = ''
      while 1:
          line = sys.stdin.readline()
          if not line:
              break
          msg = msg + line
      print("Message length is %d" % len(msg))
  
      server = SMTP('localhost')
      server.set_debuglevel(1)
      server.sendmail(fromaddr, toaddrs, msg)
      server.quit()
  