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:mod:`poplib` --- POP3 protocol client
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======================================
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:synopsis: POP3 protocol client (requires sockets).
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.. sectionauthor:: Andrew T. Csillag
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.. revised by ESR, January 2000
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**Source code:** :source:`Lib/poplib.py`
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.. index:: pair: POP3; protocol
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This module defines a class, :class:`POP3`, which encapsulates a connection to a
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POP3 server and implements the protocol as defined in :rfc:`1939`. The
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:class:`POP3` class supports both the minimal and optional command sets from
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:rfc:`1939`. The :class:`POP3` class also supports the ``STLS`` command introduced
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in :rfc:`2595` to enable encrypted communication on an already established connection.
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Additionally, this module provides a class :class:`POP3_SSL`, which provides
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support for connecting to POP3 servers that use SSL as an underlying protocol
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Note that POP3, though widely supported, is obsolescent. The implementation
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quality of POP3 servers varies widely, and too many are quite poor. If your
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mailserver supports IMAP, you would be better off using the
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:class:`imaplib.IMAP4` class, as IMAP servers tend to be better implemented.
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The :mod:`poplib` module provides two classes:
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.. class:: POP3(host, port=POP3_PORT[, timeout])
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This class implements the actual POP3 protocol. The connection is created when
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the instance is initialized. If *port* is omitted, the standard POP3 port (110)
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is used. The optional *timeout* parameter specifies a timeout in seconds for the
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connection attempt (if not specified, the global default timeout setting will
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.. class:: POP3_SSL(host, port=POP3_SSL_PORT, keyfile=None, certfile=None, timeout=None, context=None)
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This is a subclass of :class:`POP3` that connects to the server over an SSL
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encrypted socket. If *port* is not specified, 995, the standard POP3-over-SSL
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port is used. *timeout* works as in the :class:`POP3` constructor.
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*context* is an optional :class:`ssl.SSLContext` object which allows
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bundling SSL configuration options, certificates and private keys into a
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single (potentially long-lived) structure. Please read :ref:`ssl-security`
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*keyfile* and *certfile* are a legacy alternative to *context* - they can
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point to PEM-formatted private key and certificate chain files,
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respectively, for the SSL connection.
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.. versionchanged:: 3.2
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*context* parameter added.
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.. versionchanged:: 3.4
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The class now supports hostname check with
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:attr:`ssl.SSLContext.check_hostname` and *Server Name Indication* (see
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One exception is defined as an attribute of the :mod:`poplib` module:
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.. exception:: error_proto
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Exception raised on any errors from this module (errors from :mod:`socket`
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module are not caught). The reason for the exception is passed to the
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constructor as a string.
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The standard Python IMAP module.
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`Frequently Asked Questions About Fetchmail <http://www.catb.org/~esr/fetchmail/fetchmail-FAQ.html>`_
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The FAQ for the :program:`fetchmail` POP/IMAP client collects information on
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POP3 server variations and RFC noncompliance that may be useful if you need to
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write an application based on the POP protocol.
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All POP3 commands are represented by methods of the same name, in lower-case;
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most return the response text sent by the server.
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An :class:`POP3` instance has the following methods:
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.. method:: POP3.set_debuglevel(level)
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Set the instance's debugging level. This controls the amount of debugging
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output printed. The default, ``0``, produces no debugging output. A value of
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``1`` produces a moderate amount of debugging output, generally a single line
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per request. A value of ``2`` or higher produces the maximum amount of
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debugging output, logging each line sent and received on the control connection.
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.. method:: POP3.getwelcome()
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Returns the greeting string sent by the POP3 server.
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.. method:: POP3.capa()
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Query the server's capabilities as specified in :rfc:`2449`.
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Returns a dictionary in the form ``{'name': ['param'...]}``.
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.. versionadded:: 3.4
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.. method:: POP3.user(username)
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Send user command, response should indicate that a password is required.
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.. method:: POP3.pass_(password)
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Send password, response includes message count and mailbox size. Note: the
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mailbox on the server is locked until :meth:`~poplib.quit` is called.
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.. method:: POP3.apop(user, secret)
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Use the more secure APOP authentication to log into the POP3 server.
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.. method:: POP3.rpop(user)
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Use RPOP authentication (similar to UNIX r-commands) to log into POP3 server.
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.. method:: POP3.stat()
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Get mailbox status. The result is a tuple of 2 integers: ``(message count,
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.. method:: POP3.list([which])
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Request message list, result is in the form ``(response, ['mesg_num octets',
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...], octets)``. If *which* is set, it is the message to list.
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.. method:: POP3.retr(which)
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Retrieve whole message number *which*, and set its seen flag. Result is in form
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``(response, ['line', ...], octets)``.
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.. method:: POP3.dele(which)
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Flag message number *which* for deletion. On most servers deletions are not
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actually performed until QUIT (the major exception is Eudora QPOP, which
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deliberately violates the RFCs by doing pending deletes on any disconnect).
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.. method:: POP3.rset()
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Remove any deletion marks for the mailbox.
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.. method:: POP3.noop()
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Do nothing. Might be used as a keep-alive.
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.. method:: POP3.quit()
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Signoff: commit changes, unlock mailbox, drop connection.
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.. method:: POP3.top(which, howmuch)
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Retrieves the message header plus *howmuch* lines of the message after the
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header of message number *which*. Result is in form ``(response, ['line', ...],
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The POP3 TOP command this method uses, unlike the RETR command, doesn't set the
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message's seen flag; unfortunately, TOP is poorly specified in the RFCs and is
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frequently broken in off-brand servers. Test this method by hand against the
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POP3 servers you will use before trusting it.
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.. method:: POP3.uidl(which=None)
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Return message digest (unique id) list. If *which* is specified, result contains
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the unique id for that message in the form ``'response mesgnum uid``, otherwise
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result is list ``(response, ['mesgnum uid', ...], octets)``.
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.. method:: POP3.utf8()
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Try to switch to UTF-8 mode. Returns the server response if successful,
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raises :class:`error_proto` if not. Specified in :RFC:`6856`.
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.. versionadded:: 3.5
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.. method:: POP3.stls(context=None)
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Start a TLS session on the active connection as specified in :rfc:`2595`.
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This is only allowed before user authentication
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*context* parameter is a :class:`ssl.SSLContext` object which allows
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bundling SSL configuration options, certificates and private keys into
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a single (potentially long-lived) structure. Please read :ref:`ssl-security`
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This method supports hostname checking via
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:attr:`ssl.SSLContext.check_hostname` and *Server Name Indication* (see
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:data:`ssl.HAS_SNI`).
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.. versionadded:: 3.4
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Instances of :class:`POP3_SSL` have no additional methods. The interface of this
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subclass is identical to its parent.
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Here is a minimal example (without error checking) that opens a mailbox and
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retrieves and prints all messages::
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import getpass, poplib
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M = poplib.POP3('localhost')
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M.user(getpass.getuser())
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M.pass_(getpass.getpass())
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numMessages = len(M.list()[1])
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for i in range(numMessages):
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for j in M.retr(i+1)[1]:
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At the end of the module, there is a test section that contains a more extensive