:mod:`imaplib` --- IMAP4 protocol client
========================================

.. module:: imaplib
   :synopsis: IMAP4 protocol client (requires sockets).

.. moduleauthor:: Piers Lauder <piers@communitysolutions.com.au>
.. sectionauthor:: Piers Lauder <piers@communitysolutions.com.au>
.. revised by ESR, January 2000
.. changes for IMAP4_SSL by Tino Lange <Tino.Lange@isg.de>, March 2002
.. changes for IMAP4_stream by Piers Lauder <piers@communitysolutions.com.au>,
   November 2002

**Source code:** :source:`Lib/imaplib.py`

.. index::
   pair: IMAP4; protocol
   pair: IMAP4_SSL; protocol
   pair: IMAP4_stream; protocol

--------------

This module defines three classes, :class:`IMAP4`, :class:`IMAP4_SSL` and
:class:`IMAP4_stream`, which encapsulate a connection to an IMAP4 server and
implement a large subset of the IMAP4rev1 client protocol as defined in
:rfc:`2060`. It is backward compatible with IMAP4 (:rfc:`1730`) servers, but
note that the ``STATUS`` command is not supported in IMAP4.

Three classes are provided by the :mod:`imaplib` module, :class:`IMAP4` is the
base class:


.. class:: IMAP4(host='', port=IMAP4_PORT)

   This class implements the actual IMAP4 protocol.  The connection is created and
   protocol version (IMAP4 or IMAP4rev1) is determined when the instance is
   initialized. If *host* is not specified, ``''`` (the local host) is used. If
   *port* is omitted, the standard IMAP4 port (143) is used.

   The :class:`IMAP4` class supports the :keyword:`with` statement.  When used
   like this, the IMAP4 ``LOGOUT`` command is issued automatically when the
   :keyword:`with` statement exits.  E.g.::

    >>> from imaplib import IMAP4
    >>> with IMAP4("domain.org") as M:
    ...     M.noop()
    ...
    ('OK', [b'Nothing Accomplished. d25if65hy903weo.87'])

   .. versionchanged:: 3.5
      Support for the :keyword:`with` statement was added.

Three exceptions are defined as attributes of the :class:`IMAP4` class:


.. exception:: IMAP4.error

   Exception raised on any errors.  The reason for the exception is passed to the
   constructor as a string.


.. exception:: IMAP4.abort

   IMAP4 server errors cause this exception to be raised.  This is a sub-class of
   :exc:`IMAP4.error`.  Note that closing the instance and instantiating a new one
   will usually allow recovery from this exception.


.. exception:: IMAP4.readonly

   This exception is raised when a writable mailbox has its status changed by the
   server.  This is a sub-class of :exc:`IMAP4.error`.  Some other client now has
   write permission, and the mailbox will need to be re-opened to re-obtain write
   permission.


There's also a subclass for secure connections:


.. class:: IMAP4_SSL(host='', port=IMAP4_SSL_PORT, keyfile=None, \
                     certfile=None, ssl_context=None)

   This is a subclass derived from :class:`IMAP4` 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 IMAP4-over-SSL port (993) is used.
   *ssl_context* is a :class:`ssl.SSLContext` object which allows bundling
   SSL configuration options, certificates and private keys into a single
   (potentially long-lived) structure.  Please read :ref:`ssl-security` for
   best practices.

   *keyfile* and *certfile* are a legacy alternative to *ssl_context* - they
   can point to PEM-formatted private key and certificate chain files for
   the SSL connection.  Note that the *keyfile*/*certfile* parameters are
   mutually exclusive with *ssl_context*, a :class:`ValueError` is raised
   if *keyfile*/*certfile* is provided along with *ssl_context*.

   .. versionchanged:: 3.3
      *ssl_context* parameter added.

   .. versionchanged:: 3.4
      The class now supports hostname check with
      :attr:`ssl.SSLContext.check_hostname` and *Server Name Indication* (see
      :data:`ssl.HAS_SNI`).

   .. deprecated:: 3.6

       *keyfile* and *certfile* are deprecated in favor of *ssl_context*.
       Please use :meth:`ssl.SSLContext.load_cert_chain` instead, or let
       :func:`ssl.create_default_context` select the system's trusted CA
       certificates for you.


The second subclass allows for connections created by a child process:


.. class:: IMAP4_stream(command)

   This is a subclass derived from :class:`IMAP4` that connects to the
   ``stdin/stdout`` file descriptors created by passing *command* to
   ``subprocess.Popen()``.


The following utility functions are defined:


.. function:: Internaldate2tuple(datestr)

   Parse an IMAP4 ``INTERNALDATE`` string and return corresponding local
   time.  The return value is a :class:`time.struct_time` tuple or
   ``None`` if the string has wrong format.

.. function:: Int2AP(num)

   Converts an integer into a string representation using characters from the set
   [``A`` .. ``P``].


.. function:: ParseFlags(flagstr)

   Converts an IMAP4 ``FLAGS`` response to a tuple of individual flags.


.. function:: Time2Internaldate(date_time)

   Convert *date_time* to an IMAP4 ``INTERNALDATE`` representation.
   The return value is a string in the form: ``"DD-Mmm-YYYY HH:MM:SS
   +HHMM"`` (including double-quotes).  The *date_time* argument can
   be a number (int or float) representing seconds since epoch (as
   returned by :func:`time.time`), a 9-tuple representing local time
   an instance of :class:`time.struct_time` (as returned by
   :func:`time.localtime`), an aware instance of
   :class:`datetime.datetime`, or a double-quoted string.  In the last
   case, it is assumed to already be in the correct format.

Note that IMAP4 message numbers change as the mailbox changes; in particular,
after an ``EXPUNGE`` command performs deletions the remaining messages are
renumbered. So it is highly advisable to use UIDs instead, with the UID command.

At the end of the module, there is a test section that contains a more extensive
example of usage.


.. seealso::

   Documents describing the protocol, and sources and binaries  for servers
   implementing it, can all be found at the University of Washington's *IMAP
   Information Center* (https://www.washington.edu/imap/).


.. _imap4-objects:

IMAP4 Objects
-------------

All IMAP4rev1 commands are represented by methods of the same name, either
upper-case or lower-case.

All arguments to commands are converted to strings, except for ``AUTHENTICATE``,
and the last argument to ``APPEND`` which is passed as an IMAP4 literal.  If
necessary (the string contains IMAP4 protocol-sensitive characters and isn't
enclosed with either parentheses or double quotes) each string is quoted.
However, the *password* argument to the ``LOGIN`` command is always quoted. If
you want to avoid having an argument string quoted (eg: the *flags* argument to
``STORE``) then enclose the string in parentheses (eg: ``r'(\Deleted)'``).

Each command returns a tuple: ``(type, [data, ...])`` where *type* is usually
``'OK'`` or ``'NO'``, and *data* is either the text from the command response,
or mandated results from the command. Each *data* is either a string, or a
tuple. If a tuple, then the first part is the header of the response, and the
second part contains the data (ie: 'literal' value).

The *message_set* options to commands below is a string specifying one or more
messages to be acted upon.  It may be a simple message number (``'1'``), a range
of message numbers (``'2:4'``), or a group of non-contiguous ranges separated by
commas (``'1:3,6:9'``).  A range can contain an asterisk to indicate an infinite
upper bound (``'3:*'``).

An :class:`IMAP4` instance has the following methods:


.. method:: IMAP4.append(mailbox, flags, date_time, message)

   Append *message* to named mailbox.


.. method:: IMAP4.authenticate(mechanism, authobject)

   Authenticate command --- requires response processing.

   *mechanism* specifies which authentication mechanism is to be used - it should
   appear in the instance variable ``capabilities`` in the form ``AUTH=mechanism``.

   *authobject* must be a callable object::

      data = authobject(response)

   It will be called to process server continuation responses; the *response*
   argument it is passed will be ``bytes``.  It should return ``bytes`` *data*
   that will be base64 encoded and sent to the server.  It should return
   ``None`` if the client abort response ``*`` should be sent instead.

   .. versionchanged:: 3.5
      string usernames and passwords are now encoded to ``utf-8`` instead of
      being limited to ASCII.


.. method:: IMAP4.check()

   Checkpoint mailbox on server.


.. method:: IMAP4.close()

   Close currently selected mailbox. Deleted messages are removed from writable
   mailbox. This is the recommended command before ``LOGOUT``.


.. method:: IMAP4.copy(message_set, new_mailbox)

   Copy *message_set* messages onto end of *new_mailbox*.


.. method:: IMAP4.create(mailbox)

   Create new mailbox named *mailbox*.


.. method:: IMAP4.delete(mailbox)

   Delete old mailbox named *mailbox*.


.. method:: IMAP4.deleteacl(mailbox, who)

   Delete the ACLs (remove any rights) set for who on mailbox.


.. method:: IMAP4.enable(capability)

   Enable *capability* (see :rfc:`5161`).  Most capabilities do not need to be
   enabled.  Currently only the ``UTF8=ACCEPT`` capability is supported
   (see :RFC:`6855`).

   .. versionadded:: 3.5
      The :meth:`enable` method itself, and :RFC:`6855` support.


.. method:: IMAP4.expunge()

   Permanently remove deleted items from selected mailbox. Generates an ``EXPUNGE``
   response for each deleted message. Returned data contains a list of ``EXPUNGE``
   message numbers in order received.


.. method:: IMAP4.fetch(message_set, message_parts)

   Fetch (parts of) messages.  *message_parts* should be a string of message part
   names enclosed within parentheses, eg: ``"(UID BODY[TEXT])"``.  Returned data
   are tuples of message part envelope and data.


.. method:: IMAP4.getacl(mailbox)

   Get the ``ACL``\ s for *mailbox*. The method is non-standard, but is supported
   by the ``Cyrus`` server.


.. method:: IMAP4.getannotation(mailbox, entry, attribute)

   Retrieve the specified ``ANNOTATION``\ s for *mailbox*. The method is
   non-standard, but is supported by the ``Cyrus`` server.


.. method:: IMAP4.getquota(root)

   Get the ``quota`` *root*'s resource usage and limits. This method is part of the
   IMAP4 QUOTA extension defined in rfc2087.


.. method:: IMAP4.getquotaroot(mailbox)

   Get the list of ``quota`` ``roots`` for the named *mailbox*. This method is part
   of the IMAP4 QUOTA extension defined in rfc2087.


.. method:: IMAP4.list([directory[, pattern]])

   List mailbox names in *directory* matching *pattern*.  *directory* defaults to
   the top-level mail folder, and *pattern* defaults to match anything.  Returned
   data contains a list of ``LIST`` responses.


.. method:: IMAP4.login(user, password)

   Identify the client using a plaintext password. The *password* will be quoted.


.. method:: IMAP4.login_cram_md5(user, password)

   Force use of ``CRAM-MD5`` authentication when identifying the client to protect
   the password.  Will only work if the server ``CAPABILITY`` response includes the
   phrase ``AUTH=CRAM-MD5``.


.. method:: IMAP4.logout()

   Shutdown connection to server. Returns server ``BYE`` response.


.. method:: IMAP4.lsub(directory='""', pattern='*')

   List subscribed mailbox names in directory matching pattern. *directory*
   defaults to the top level directory and *pattern* defaults to match any mailbox.
   Returned data are tuples of message part envelope and data.


.. method:: IMAP4.myrights(mailbox)

   Show my ACLs for a mailbox (i.e. the rights that I have on mailbox).


.. method:: IMAP4.namespace()

   Returns IMAP namespaces as defined in :rfc:`2342`.


.. method:: IMAP4.noop()

   Send ``NOOP`` to server.


.. method:: IMAP4.open(host, port)

   Opens socket to *port* at *host*.  This method is implicitly called by
   the :class:`IMAP4` constructor.  The connection objects established by this
   method will be used in the :meth:`IMAP4.read`, :meth:`IMAP4.readline`,
   :meth:`IMAP4.send`, and :meth:`IMAP4.shutdown` methods.  You may override
   this method.


.. method:: IMAP4.partial(message_num, message_part, start, length)

   Fetch truncated part of a message. Returned data is a tuple of message part
   envelope and data.


.. method:: IMAP4.proxyauth(user)

   Assume authentication as *user*. Allows an authorised administrator to proxy
   into any user's mailbox.


.. method:: IMAP4.read(size)

   Reads *size* bytes from the remote server. You may override this method.


.. method:: IMAP4.readline()

   Reads one line from the remote server. You may override this method.


.. method:: IMAP4.recent()

   Prompt server for an update. Returned data is ``None`` if no new messages, else
   value of ``RECENT`` response.


.. method:: IMAP4.rename(oldmailbox, newmailbox)

   Rename mailbox named *oldmailbox* to *newmailbox*.


.. method:: IMAP4.response(code)

   Return data for response *code* if received, or ``None``. Returns the given
   code, instead of the usual type.


.. method:: IMAP4.search(charset, criterion[, ...])

   Search mailbox for matching messages.  *charset* may be ``None``, in which case
   no ``CHARSET`` will be specified in the request to the server.  The IMAP
   protocol requires that at least one criterion be specified; an exception will be
   raised when the server returns an error.  *charset* must be ``None`` if
   the ``UTF8=ACCEPT`` capability was enabled using the :meth:`enable`
   command.

   Example::

      # M is a connected IMAP4 instance...
      typ, msgnums = M.search(None, 'FROM', '"LDJ"')

      # or:
      typ, msgnums = M.search(None, '(FROM "LDJ")')


.. method:: IMAP4.select(mailbox='INBOX', readonly=False)

   Select a mailbox. Returned data is the count of messages in *mailbox*
   (``EXISTS`` response).  The default *mailbox* is ``'INBOX'``.  If the *readonly*
   flag is set, modifications to the mailbox are not allowed.


.. method:: IMAP4.send(data)

   Sends ``data`` to the remote server. You may override this method.


.. method:: IMAP4.setacl(mailbox, who, what)

   Set an ``ACL`` for *mailbox*. The method is non-standard, but is supported by
   the ``Cyrus`` server.


.. method:: IMAP4.setannotation(mailbox, entry, attribute[, ...])

   Set ``ANNOTATION``\ s for *mailbox*. The method is non-standard, but is
   supported by the ``Cyrus`` server.


.. method:: IMAP4.setquota(root, limits)

   Set the ``quota`` *root*'s resource *limits*. This method is part of the IMAP4
   QUOTA extension defined in rfc2087.


.. method:: IMAP4.shutdown()

   Close connection established in ``open``.  This method is implicitly
   called by :meth:`IMAP4.logout`.  You may override this method.


.. method:: IMAP4.socket()

   Returns socket instance used to connect to server.


.. method:: IMAP4.sort(sort_criteria, charset, search_criterion[, ...])

   The ``sort`` command is a variant of ``search`` with sorting semantics for the
   results.  Returned data contains a space separated list of matching message
   numbers.

   Sort has two arguments before the *search_criterion* argument(s); a
   parenthesized list of *sort_criteria*, and the searching *charset*.  Note that
   unlike ``search``, the searching *charset* argument is mandatory.  There is also
   a ``uid sort`` command which corresponds to ``sort`` the way that ``uid search``
   corresponds to ``search``.  The ``sort`` command first searches the mailbox for
   messages that match the given searching criteria using the charset argument for
   the interpretation of strings in the searching criteria.  It then returns the
   numbers of matching messages.

   This is an ``IMAP4rev1`` extension command.


.. method:: IMAP4.starttls(ssl_context=None)

   Send a ``STARTTLS`` command.  The *ssl_context* argument is optional
   and should be a :class:`ssl.SSLContext` object.  This will enable
   encryption on the IMAP connection.  Please read :ref:`ssl-security` for
   best practices.

   .. versionadded:: 3.2

   .. versionchanged:: 3.4
      The method now supports hostname check with
      :attr:`ssl.SSLContext.check_hostname` and *Server Name Indication* (see
      :data:`ssl.HAS_SNI`).


.. method:: IMAP4.status(mailbox, names)

   Request named status conditions for *mailbox*.


.. method:: IMAP4.store(message_set, command, flag_list)

   Alters flag dispositions for messages in mailbox.  *command* is specified by
   section 6.4.6 of :rfc:`2060` as being one of "FLAGS", "+FLAGS", or "-FLAGS",
   optionally with a suffix of ".SILENT".

   For example, to set the delete flag on all messages::

      typ, data = M.search(None, 'ALL')
      for num in data[0].split():
         M.store(num, '+FLAGS', '\\Deleted')
      M.expunge()

   .. note::

      Creating flags containing ']' (for example: "[test]") violates
      :rfc:`3501` (the IMAP protocol).  However, imaplib has historically
      allowed creation of such tags, and popular IMAP servers, such as Gmail,
      accept and produce such flags.  There are non-Python programs which also
      create such tags.  Although it is an RFC violation and IMAP clients and
      servers are supposed to be strict, imaplib nonetheless continues to allow
      such tags to be created for backward compatibility reasons, and as of
      python 3.6, handles them if they are sent from the server, since this
      improves real-world compatibility.

.. method:: IMAP4.subscribe(mailbox)

   Subscribe to new mailbox.


.. method:: IMAP4.thread(threading_algorithm, charset, search_criterion[, ...])

   The ``thread`` command is a variant of ``search`` with threading semantics for
   the results.  Returned data contains a space separated list of thread members.

   Thread members consist of zero or more messages numbers, delimited by spaces,
   indicating successive parent and child.

   Thread has two arguments before the *search_criterion* argument(s); a
   *threading_algorithm*, and the searching *charset*.  Note that unlike
   ``search``, the searching *charset* argument is mandatory.  There is also a
   ``uid thread`` command which corresponds to ``thread`` the way that ``uid
   search`` corresponds to ``search``.  The ``thread`` command first searches the
   mailbox for messages that match the given searching criteria using the charset
   argument for the interpretation of strings in the searching criteria. It then
   returns the matching messages threaded according to the specified threading
   algorithm.

   This is an ``IMAP4rev1`` extension command.


.. method:: IMAP4.uid(command, arg[, ...])

   Execute command args with messages identified by UID, rather than message
   number.  Returns response appropriate to command.  At least one argument must be
   supplied; if none are provided, the server will return an error and an exception
   will be raised.


.. method:: IMAP4.unsubscribe(mailbox)

   Unsubscribe from old mailbox.


.. method:: IMAP4.xatom(name[, ...])

   Allow simple extension commands notified by server in ``CAPABILITY`` response.


The following attributes are defined on instances of :class:`IMAP4`:

.. attribute:: IMAP4.PROTOCOL_VERSION

   The most recent supported protocol in the ``CAPABILITY`` response from the
   server.


.. attribute:: IMAP4.debug

   Integer value to control debugging output.  The initialize value is taken from
   the module variable ``Debug``.  Values greater than three trace each command.


.. attribute:: IMAP4.utf8_enabled

   Boolean value that is normally ``False``, but is set to ``True`` if an
   :meth:`enable` command is successfully issued for the ``UTF8=ACCEPT``
   capability.

   .. versionadded:: 3.5


.. _imap4-example:

IMAP4 Example
-------------

Here is a minimal example (without error checking) that opens a mailbox and
retrieves and prints all messages::

   import getpass, imaplib

   M = imaplib.IMAP4()
   M.login(getpass.getuser(), getpass.getpass())
   M.select()
   typ, data = M.search(None, 'ALL')
   for num in data[0].split():
       typ, data = M.fetch(num, '(RFC822)')
       print('Message %s\n%s\n' % (num, data[0][1]))
   M.close()
   M.logout()

