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:mod:`smtplib` --- SMTP protocol client
=======================================
.. module:: smtplib
:synopsis: SMTP protocol client (requires sockets).
.. sectionauthor:: Eric S. Raymond <esr@snark.thyrsus.com>
.. index::
pair: SMTP; protocol
single: Simple Mail Transfer Protocol
The :mod:`smtplib` module defines an SMTP client session object that can be used
to send mail to any Internet machine with an SMTP or ESMTP listener daemon. For
details of SMTP and ESMTP operation, consult :rfc:`821` (Simple Mail Transfer
Protocol) and :rfc:`1869` (SMTP Service Extensions).
.. class:: SMTP([host[, port[, local_hostname[, timeout]]]])
A :class:`SMTP` instance encapsulates an SMTP connection. It has methods
that support a full repertoire of SMTP and ESMTP operations. If the optional
host and port parameters are given, the SMTP :meth:`connect` method is called
with those parameters during initialization. An :exc:`SMTPConnectError` is
raised if the specified host doesn't respond correctly. The optional
*timeout* parameter specifies a timeout in seconds for blocking operations
like the connection attempt (if not specified, the global default timeout
setting will be used).
For normal use, you should only require the initialization/connect,
:meth:`sendmail`, and :meth:`quit` methods. An example is included below.
.. versionchanged:: 2.6
*timeout* was added.
.. class:: SMTP_SSL([host[, port[, local_hostname[, keyfile[, certfile[, timeout]]]]]])
A :class:`SMTP_SSL` instance behaves exactly the same as instances of
:class:`SMTP`. :class:`SMTP_SSL` should be used for situations where SSL is
required from the beginning of the connection and using :meth:`starttls` is
not appropriate. If *host* is not specified, the local host is used. If
*port* is omitted, the standard SMTP-over-SSL port (465) is used. *keyfile*
and *certfile* are also optional, and can contain a PEM formatted private key
and certificate chain file for the SSL connection. The optional *timeout*
parameter specifies a timeout in seconds for blocking operations like the
connection attempt (if not specified, the global default timeout setting
will be used).
.. versionchanged:: 2.6
*timeout* was added.
.. class:: LMTP([host[, port[, local_hostname]]])
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 :meth:`connect`
method must support that as well as a regular host:port server. To specify a
Unix socket, you must use an absolute path for *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.
.. versionadded:: 2.6
A nice selection of exceptions is defined as well:
.. exception:: SMTPException
Base exception class for all exceptions raised by this module.
.. exception:: SMTPServerDisconnected
This exception is raised when the server unexpectedly disconnects, or when an
attempt is made to use the :class:`SMTP` instance before connecting it to a
server.
.. exception:: SMTPResponseException
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 :attr:`smtp_code` attribute of the error, and the
:attr:`smtp_error` attribute is set to the error message.
.. exception:: SMTPSenderRefused
Sender address refused. In addition to the attributes set by on all
:exc:`SMTPResponseException` exceptions, this sets 'sender' to the string that
the SMTP server refused.
.. exception:: SMTPRecipientsRefused
All recipient addresses refused. The errors for each recipient are accessible
through the attribute :attr:`recipients`, which is a dictionary of exactly the
same sort as :meth:`SMTP.sendmail` returns.
.. exception:: SMTPDataError
The SMTP server refused to accept the message data.
.. exception:: SMTPConnectError
Error occurred during establishment of a connection with the server.
.. exception:: SMTPHeloError
The server refused our ``HELO`` message.
.. exception:: SMTPAuthenticationError
SMTP authentication went wrong. Most probably the server didn't accept the
username/password combination provided.
.. seealso::
:rfc:`821` - Simple Mail Transfer Protocol
Protocol definition for SMTP. This document covers the model, operating
procedure, and protocol details for SMTP.
:rfc:`1869` - SMTP Service Extensions
Definition of the ESMTP extensions for SMTP. This describes a framework for
extending SMTP with new commands, supporting dynamic discovery of the commands
provided by the server, and defines a few additional commands.
.. _smtp-objects:
SMTP Objects
------------
An :class:`SMTP` instance has the following methods:
.. method:: SMTP.set_debuglevel(level)
Set the debug output level. A true value for *level* results in debug messages
for connection and for all messages sent to and received from the server.
.. method:: SMTP.connect([host[, port]])
Connect to a host on a given port. The defaults are to connect to the local
host at the standard SMTP port (25). If the hostname ends with a colon (``':'``)
followed by a number, that suffix will be stripped off and the number
interpreted as the port number to use. This method is automatically invoked by
the constructor if a host is specified during instantiation.
.. method:: SMTP.docmd(cmd, [, argstring])
Send a command *cmd* to the server. The optional argument *argstring* is simply
concatenated to the command, separated by a space.
This returns a 2-tuple composed of a numeric response code and the actual
response line (multiline responses are joined into one long line.)
In normal operation it should not be necessary to call this method explicitly.
It is used to implement other methods and may be useful for testing private
extensions.
If the connection to the server is lost while waiting for the reply,
:exc:`SMTPServerDisconnected` will be raised.
.. method:: SMTP.helo([hostname])
Identify yourself to the SMTP server using ``HELO``. The hostname argument
defaults to the fully qualified domain name of the local host.
The message returned by the server is stored as the :attr:`helo_resp` attribute
of the object.
In normal operation it should not be necessary to call this method explicitly.
It will be implicitly called by the :meth:`sendmail` when necessary.
.. method:: SMTP.ehlo([hostname])
Identify yourself to an ESMTP server using ``EHLO``. The hostname argument
defaults to the fully qualified domain name of the local host. Examine the
response for ESMTP option and store them for use by :meth:`has_extn`.
Also sets several informational attributes: the message returned by
the server is stored as the :attr:`ehlo_resp` attribute, :attr:`does_esmtp`
is set to true or false depending on whether the server supports ESMTP, and
:attr:`esmtp_features` will be a dictionary containing the names of the
SMTP service extensions this server supports, and their
parameters (if any).
Unless you wish to use :meth:`has_extn` before sending mail, it should not be
necessary to call this method explicitly. It will be implicitly called by
:meth:`sendmail` when necessary.
.. method:: SMTP.ehlo_or_helo_if_needed()
This method call :meth:`ehlo` and or :meth:`helo` if there has been no
previous ``EHLO`` or ``HELO`` command this session. It tries ESMTP ``EHLO``
first.
:exc:`SMTPHeloError`
The server didn't reply properly to the ``HELO`` greeting.
.. versionadded:: 2.6
.. method:: SMTP.has_extn(name)
Return :const:`True` if *name* is in the set of SMTP service extensions returned
by the server, :const:`False` otherwise. Case is ignored.
.. method:: SMTP.verify(address)
Check the validity of an address on this server using SMTP ``VRFY``. Returns a
tuple consisting of code 250 and a full :rfc:`822` address (including human
name) if the user address is valid. Otherwise returns an SMTP error code of 400
or greater and an error string.
.. note::
Many sites disable SMTP ``VRFY`` in order to foil spammers.
.. method:: SMTP.login(user, password)
Log in on an SMTP server that requires authentication. The arguments are the
username and the password to authenticate with. 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, or
may raise the following exceptions:
:exc:`SMTPHeloError`
The server didn't reply properly to the ``HELO`` greeting.
:exc:`SMTPAuthenticationError`
The server didn't accept the username/password combination.
:exc:`SMTPException`
No suitable authentication method was found.
.. method:: SMTP.starttls([keyfile[, certfile]])
Put the SMTP connection in TLS (Transport Layer Security) mode. All SMTP
commands that follow will be encrypted. You should then call :meth:`ehlo`
again.
If *keyfile* and *certfile* are provided, these are passed to the :mod:`socket`
module's :func:`ssl` function.
If there has been no previous ``EHLO`` or ``HELO`` command this session,
this method tries ESMTP ``EHLO`` first.
.. versionchanged:: 2.6
:exc:`SMTPHeloError`
The server didn't reply properly to the ``HELO`` greeting.
:exc:`SMTPException`
The server does not support the STARTTLS extension.
.. versionchanged:: 2.6
:exc:`RuntimeError`
SSL/TLS support is not available to your Python interpreter.
.. method:: SMTP.sendmail(from_addr, to_addrs, msg[, mail_options, rcpt_options])
Send mail. The required arguments are an :rfc:`822` from-address string, a list
of :rfc:`822` to-address strings (a bare string will be treated as a list with 1
address), and a message string. The caller may pass a list of ESMTP options
(such as ``8bitmime``) to be used in ``MAIL FROM`` commands as *mail_options*.
ESMTP options (such as ``DSN`` commands) that should be used with all ``RCPT``
commands can be passed as *rcpt_options*. (If you need to use different ESMTP
options to different recipients you have to use the low-level methods such as
:meth:`mail`, :meth:`rcpt` and :meth:`data` to send the message.)
.. note::
The *from_addr* and *to_addrs* parameters are used to construct the message
envelope used by the transport agents. The :class:`SMTP` does not modify the
message headers in any way.
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 the option is in the
feature set the server advertises). 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. Otherwise it will raise an exception. That is, if this method does
not raise an exception, then someone should get your mail. If this method does
not raise an exception, 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:
:exc:`SMTPRecipientsRefused`
All recipients were refused. Nobody got the mail. The :attr:`recipients`
attribute of the exception object is a dictionary with information about the
refused recipients (like the one returned when at least one recipient was
accepted).
:exc:`SMTPHeloError`
The server didn't reply properly to the ``HELO`` greeting.
:exc:`SMTPSenderRefused`
The server didn't accept the *from_addr*.
:exc:`SMTPDataError`
The server replied with an unexpected error code (other than a refusal of a
recipient).
Unless otherwise noted, the connection will be open even after an exception is
raised.
.. method:: SMTP.quit()
Terminate the SMTP session and close the connection. Return the result of
the SMTP ``QUIT`` command.
.. versionchanged:: 2.6
Return a value.
Low-level methods corresponding to the standard SMTP/ESMTP commands ``HELP``,
``RSET``, ``NOOP``, ``MAIL``, ``RCPT``, and ``DATA`` are also supported.
Normally these do not need to be called directly, so they are not documented
here. For details, consult the module code.
.. _smtp-example:
SMTP Example
------------
This example prompts the user for addresses needed in the message envelope ('To'
and 'From' addresses), and the message to be delivered. Note that the headers
to be included with the message must be included in the message as entered; this
example doesn't do any processing of the :rfc:`822` headers. In particular, the
'To' and 'From' addresses must be included in the message headers explicitly. ::
import smtplib
def prompt(prompt):
return raw_input(prompt).strip()
fromaddr = prompt("From: ")
toaddrs = prompt("To: ").split()
print "Enter message, end with ^D (Unix) or ^Z (Windows):"
# Add the From: and To: headers at the start!
msg = ("From: %s\r\nTo: %s\r\n\r\n"
% (fromaddr, ", ".join(toaddrs)))
while 1:
try:
line = raw_input()
except EOFError:
break
if not line:
break
msg = msg + line
print "Message length is " + repr(len(msg))
server = smtplib.SMTP('localhost')
server.set_debuglevel(1)
server.sendmail(fromaddr, toaddrs, msg)
server.quit()
.. note::
In general, you will want to use the :mod:`email` package's features to
construct an email message, which you can then convert to a string and send
via :meth:`sendmail`; see :ref:`email-examples`.
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