symbian-qemu-0.9.1-12/python-2.6.1/Doc/library/email.rst
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     1 :mod:`email` --- An email and MIME handling package
       
     2 ===================================================
       
     3 
       
     4 .. module:: email
       
     5    :synopsis: Package supporting the parsing, manipulating, and generating email messages,
       
     6               including MIME documents.
       
     7 .. moduleauthor:: Barry A. Warsaw <barry@python.org>
       
     8 .. sectionauthor:: Barry A. Warsaw <barry@python.org>
       
     9 .. Copyright (C) 2001-2007 Python Software Foundation
       
    10 
       
    11 
       
    12 .. versionadded:: 2.2
       
    13 
       
    14 The :mod:`email` package is a library for managing email messages, including
       
    15 MIME and other :rfc:`2822`\ -based message documents.  It subsumes most of the
       
    16 functionality in several older standard modules such as :mod:`rfc822`,
       
    17 :mod:`mimetools`, :mod:`multifile`, and other non-standard packages such as
       
    18 :mod:`mimecntl`.  It is specifically *not* designed to do any sending of email
       
    19 messages to SMTP (:rfc:`2821`), NNTP, or other servers; those are functions of
       
    20 modules such as :mod:`smtplib` and :mod:`nntplib`. The :mod:`email` package
       
    21 attempts to be as RFC-compliant as possible, supporting in addition to
       
    22 :rfc:`2822`, such MIME-related RFCs as :rfc:`2045`, :rfc:`2046`, :rfc:`2047`,
       
    23 and :rfc:`2231`.
       
    24 
       
    25 The primary distinguishing feature of the :mod:`email` package is that it splits
       
    26 the parsing and generating of email messages from the internal *object model*
       
    27 representation of email.  Applications using the :mod:`email` package deal
       
    28 primarily with objects; you can add sub-objects to messages, remove sub-objects
       
    29 from messages, completely re-arrange the contents, etc.  There is a separate
       
    30 parser and a separate generator which handles the transformation from flat text
       
    31 to the object model, and then back to flat text again.  There are also handy
       
    32 subclasses for some common MIME object types, and a few miscellaneous utilities
       
    33 that help with such common tasks as extracting and parsing message field values,
       
    34 creating RFC-compliant dates, etc.
       
    35 
       
    36 The following sections describe the functionality of the :mod:`email` package.
       
    37 The ordering follows a progression that should be common in applications: an
       
    38 email message is read as flat text from a file or other source, the text is
       
    39 parsed to produce the object structure of the email message, this structure is
       
    40 manipulated, and finally, the object tree is rendered back into flat text.
       
    41 
       
    42 It is perfectly feasible to create the object structure out of whole cloth ---
       
    43 i.e. completely from scratch.  From there, a similar progression can be taken as
       
    44 above.
       
    45 
       
    46 Also included are detailed specifications of all the classes and modules that
       
    47 the :mod:`email` package provides, the exception classes you might encounter
       
    48 while using the :mod:`email` package, some auxiliary utilities, and a few
       
    49 examples.  For users of the older :mod:`mimelib` package, or previous versions
       
    50 of the :mod:`email` package, a section on differences and porting is provided.
       
    51 
       
    52 Contents of the :mod:`email` package documentation:
       
    53 
       
    54 .. toctree::
       
    55 
       
    56    email.message.rst
       
    57    email.parser.rst
       
    58    email.generator.rst
       
    59    email.mime.rst
       
    60    email.header.rst
       
    61    email.charset.rst
       
    62    email.encoders.rst
       
    63    email.errors.rst
       
    64    email.util.rst
       
    65    email.iterators.rst
       
    66    email-examples.rst
       
    67 
       
    68 
       
    69 .. seealso::
       
    70 
       
    71    Module :mod:`smtplib`
       
    72       SMTP protocol client
       
    73 
       
    74    Module :mod:`nntplib`
       
    75       NNTP protocol client
       
    76 
       
    77 
       
    78 .. _email-pkg-history:
       
    79 
       
    80 Package History
       
    81 ---------------
       
    82 
       
    83 This table describes the release history of the email package, corresponding to
       
    84 the version of Python that the package was released with.  For purposes of this
       
    85 document, when you see a note about change or added versions, these refer to the
       
    86 Python version the change was made in, *not* the email package version.  This
       
    87 table also describes the Python compatibility of each version of the package.
       
    88 
       
    89 +---------------+------------------------------+-----------------------+
       
    90 | email version | distributed with             | compatible with       |
       
    91 +===============+==============================+=======================+
       
    92 | :const:`1.x`  | Python 2.2.0 to Python 2.2.1 | *no longer supported* |
       
    93 +---------------+------------------------------+-----------------------+
       
    94 | :const:`2.5`  | Python 2.2.2+ and Python 2.3 | Python 2.1 to 2.5     |
       
    95 +---------------+------------------------------+-----------------------+
       
    96 | :const:`3.0`  | Python 2.4                   | Python 2.3 to 2.5     |
       
    97 +---------------+------------------------------+-----------------------+
       
    98 | :const:`4.0`  | Python 2.5                   | Python 2.3 to 2.5     |
       
    99 +---------------+------------------------------+-----------------------+
       
   100 
       
   101 Here are the major differences between :mod:`email` version 4 and version 3:
       
   102 
       
   103 * All modules have been renamed according to :pep:`8` standards.  For example,
       
   104   the version 3 module :mod:`email.Message` was renamed to :mod:`email.message` in
       
   105   version 4.
       
   106 
       
   107 * A new subpackage :mod:`email.mime` was added and all the version 3
       
   108   :mod:`email.MIME\*` modules were renamed and situated into the :mod:`email.mime`
       
   109   subpackage.  For example, the version 3 module :mod:`email.MIMEText` was renamed
       
   110   to :mod:`email.mime.text`.
       
   111 
       
   112   *Note that the version 3 names will continue to work until Python 2.6*.
       
   113 
       
   114 * The :mod:`email.mime.application` module was added, which contains the
       
   115   :class:`MIMEApplication` class.
       
   116 
       
   117 * Methods that were deprecated in version 3 have been removed.  These include
       
   118   :meth:`Generator.__call__`, :meth:`Message.get_type`,
       
   119   :meth:`Message.get_main_type`, :meth:`Message.get_subtype`.
       
   120 
       
   121 * Fixes have been added for :rfc:`2231` support which can change some of the
       
   122   return types for :func:`Message.get_param` and friends.  Under some
       
   123   circumstances, values which used to return a 3-tuple now return simple strings
       
   124   (specifically, if all extended parameter segments were unencoded, there is no
       
   125   language and charset designation expected, so the return type is now a simple
       
   126   string).  Also, %-decoding used to be done for both encoded and unencoded
       
   127   segments; this decoding is now done only for encoded segments.
       
   128 
       
   129 Here are the major differences between :mod:`email` version 3 and version 2:
       
   130 
       
   131 * The :class:`FeedParser` class was introduced, and the :class:`Parser` class
       
   132   was implemented in terms of the :class:`FeedParser`.  All parsing therefore is
       
   133   non-strict, and parsing will make a best effort never to raise an exception.
       
   134   Problems found while parsing messages are stored in the message's *defect*
       
   135   attribute.
       
   136 
       
   137 * All aspects of the API which raised :exc:`DeprecationWarning`\ s in version 2
       
   138   have been removed.  These include the *_encoder* argument to the
       
   139   :class:`MIMEText` constructor, the :meth:`Message.add_payload` method, the
       
   140   :func:`Utils.dump_address_pair` function, and the functions :func:`Utils.decode`
       
   141   and :func:`Utils.encode`.
       
   142 
       
   143 * New :exc:`DeprecationWarning`\ s have been added to:
       
   144   :meth:`Generator.__call__`, :meth:`Message.get_type`,
       
   145   :meth:`Message.get_main_type`, :meth:`Message.get_subtype`, and the *strict*
       
   146   argument to the :class:`Parser` class.  These are expected to be removed in
       
   147   future versions.
       
   148 
       
   149 * Support for Pythons earlier than 2.3 has been removed.
       
   150 
       
   151 Here are the differences between :mod:`email` version 2 and version 1:
       
   152 
       
   153 * The :mod:`email.Header` and :mod:`email.Charset` modules have been added.
       
   154 
       
   155 * The pickle format for :class:`Message` instances has changed. Since this was
       
   156   never (and still isn't) formally defined, this isn't considered a backward
       
   157   incompatibility.  However if your application pickles and unpickles
       
   158   :class:`Message` instances, be aware that in :mod:`email` version 2,
       
   159   :class:`Message` instances now have private variables *_charset* and
       
   160   *_default_type*.
       
   161 
       
   162 * Several methods in the :class:`Message` class have been deprecated, or their
       
   163   signatures changed.  Also, many new methods have been added.  See the
       
   164   documentation for the :class:`Message` class for details.  The changes should be
       
   165   completely backward compatible.
       
   166 
       
   167 * The object structure has changed in the face of :mimetype:`message/rfc822`
       
   168   content types.  In :mod:`email` version 1, such a type would be represented by a
       
   169   scalar payload, i.e. the container message's :meth:`is_multipart` returned
       
   170   false, :meth:`get_payload` was not a list object, but a single :class:`Message`
       
   171   instance.
       
   172 
       
   173   This structure was inconsistent with the rest of the package, so the object
       
   174   representation for :mimetype:`message/rfc822` content types was changed.  In
       
   175   :mod:`email` version 2, the container *does* return ``True`` from
       
   176   :meth:`is_multipart`, and :meth:`get_payload` returns a list containing a single
       
   177   :class:`Message` item.
       
   178 
       
   179   Note that this is one place that backward compatibility could not be completely
       
   180   maintained.  However, if you're already testing the return type of
       
   181   :meth:`get_payload`, you should be fine.  You just need to make sure your code
       
   182   doesn't do a :meth:`set_payload` with a :class:`Message` instance on a container
       
   183   with a content type of :mimetype:`message/rfc822`.
       
   184 
       
   185 * The :class:`Parser` constructor's *strict* argument was added, and its
       
   186   :meth:`parse` and :meth:`parsestr` methods grew a *headersonly* argument.  The
       
   187   *strict* flag was also added to functions :func:`email.message_from_file` and
       
   188   :func:`email.message_from_string`.
       
   189 
       
   190 * :meth:`Generator.__call__` is deprecated; use :meth:`Generator.flatten`
       
   191   instead.  The :class:`Generator` class has also grown the :meth:`clone` method.
       
   192 
       
   193 * The :class:`DecodedGenerator` class in the :mod:`email.Generator` module was
       
   194   added.
       
   195 
       
   196 * The intermediate base classes :class:`MIMENonMultipart` and
       
   197   :class:`MIMEMultipart` have been added, and interposed in the class hierarchy
       
   198   for most of the other MIME-related derived classes.
       
   199 
       
   200 * The *_encoder* argument to the :class:`MIMEText` constructor has been
       
   201   deprecated.  Encoding  now happens implicitly based on the *_charset* argument.
       
   202 
       
   203 * The following functions in the :mod:`email.Utils` module have been deprecated:
       
   204   :func:`dump_address_pairs`, :func:`decode`, and :func:`encode`.  The following
       
   205   functions have been added to the module: :func:`make_msgid`,
       
   206   :func:`decode_rfc2231`, :func:`encode_rfc2231`, and :func:`decode_params`.
       
   207 
       
   208 * The non-public function :func:`email.Iterators._structure` was added.
       
   209 
       
   210 
       
   211 Differences from :mod:`mimelib`
       
   212 -------------------------------
       
   213 
       
   214 The :mod:`email` package was originally prototyped as a separate library called
       
   215 `mimelib <http://mimelib.sf.net/>`_. Changes have been made so that method names
       
   216 are more consistent, and some methods or modules have either been added or
       
   217 removed.  The semantics of some of the methods have also changed.  For the most
       
   218 part, any functionality available in :mod:`mimelib` is still available in the
       
   219 :mod:`email` package, albeit often in a different way.  Backward compatibility
       
   220 between the :mod:`mimelib` package and the :mod:`email` package was not a
       
   221 priority.
       
   222 
       
   223 Here is a brief description of the differences between the :mod:`mimelib` and
       
   224 the :mod:`email` packages, along with hints on how to port your applications.
       
   225 
       
   226 Of course, the most visible difference between the two packages is that the
       
   227 package name has been changed to :mod:`email`.  In addition, the top-level
       
   228 package has the following differences:
       
   229 
       
   230 * :func:`messageFromString` has been renamed to :func:`message_from_string`.
       
   231 
       
   232 * :func:`messageFromFile` has been renamed to :func:`message_from_file`.
       
   233 
       
   234 The :class:`Message` class has the following differences:
       
   235 
       
   236 * The method :meth:`asString` was renamed to :meth:`as_string`.
       
   237 
       
   238 * The method :meth:`ismultipart` was renamed to :meth:`is_multipart`.
       
   239 
       
   240 * The :meth:`get_payload` method has grown a *decode* optional argument.
       
   241 
       
   242 * The method :meth:`getall` was renamed to :meth:`get_all`.
       
   243 
       
   244 * The method :meth:`addheader` was renamed to :meth:`add_header`.
       
   245 
       
   246 * The method :meth:`gettype` was renamed to :meth:`get_type`.
       
   247 
       
   248 * The method :meth:`getmaintype` was renamed to :meth:`get_main_type`.
       
   249 
       
   250 * The method :meth:`getsubtype` was renamed to :meth:`get_subtype`.
       
   251 
       
   252 * The method :meth:`getparams` was renamed to :meth:`get_params`. Also, whereas
       
   253   :meth:`getparams` returned a list of strings, :meth:`get_params` returns a list
       
   254   of 2-tuples, effectively the key/value pairs of the parameters, split on the
       
   255   ``'='`` sign.
       
   256 
       
   257 * The method :meth:`getparam` was renamed to :meth:`get_param`.
       
   258 
       
   259 * The method :meth:`getcharsets` was renamed to :meth:`get_charsets`.
       
   260 
       
   261 * The method :meth:`getfilename` was renamed to :meth:`get_filename`.
       
   262 
       
   263 * The method :meth:`getboundary` was renamed to :meth:`get_boundary`.
       
   264 
       
   265 * The method :meth:`setboundary` was renamed to :meth:`set_boundary`.
       
   266 
       
   267 * The method :meth:`getdecodedpayload` was removed.  To get similar
       
   268   functionality, pass the value 1 to the *decode* flag of the get_payload()
       
   269   method.
       
   270 
       
   271 * The method :meth:`getpayloadastext` was removed.  Similar functionality is
       
   272   supported by the :class:`DecodedGenerator` class in the :mod:`email.generator`
       
   273   module.
       
   274 
       
   275 * The method :meth:`getbodyastext` was removed.  You can get similar
       
   276   functionality by creating an iterator with :func:`typed_subpart_iterator` in the
       
   277   :mod:`email.iterators` module.
       
   278 
       
   279 The :class:`Parser` class has no differences in its public interface. It does
       
   280 have some additional smarts to recognize :mimetype:`message/delivery-status`
       
   281 type messages, which it represents as a :class:`Message` instance containing
       
   282 separate :class:`Message` subparts for each header block in the delivery status
       
   283 notification [#]_.
       
   284 
       
   285 The :class:`Generator` class has no differences in its public interface.  There
       
   286 is a new class in the :mod:`email.generator` module though, called
       
   287 :class:`DecodedGenerator` which provides most of the functionality previously
       
   288 available in the :meth:`Message.getpayloadastext` method.
       
   289 
       
   290 The following modules and classes have been changed:
       
   291 
       
   292 * The :class:`MIMEBase` class constructor arguments *_major* and *_minor* have
       
   293   changed to *_maintype* and *_subtype* respectively.
       
   294 
       
   295 * The ``Image`` class/module has been renamed to ``MIMEImage``.  The *_minor*
       
   296   argument has been renamed to *_subtype*.
       
   297 
       
   298 * The ``Text`` class/module has been renamed to ``MIMEText``.  The *_minor*
       
   299   argument has been renamed to *_subtype*.
       
   300 
       
   301 * The ``MessageRFC822`` class/module has been renamed to ``MIMEMessage``.  Note
       
   302   that an earlier version of :mod:`mimelib` called this class/module ``RFC822``,
       
   303   but that clashed with the Python standard library module :mod:`rfc822` on some
       
   304   case-insensitive file systems.
       
   305 
       
   306   Also, the :class:`MIMEMessage` class now represents any kind of MIME message
       
   307   with main type :mimetype:`message`.  It takes an optional argument *_subtype*
       
   308   which is used to set the MIME subtype.  *_subtype* defaults to
       
   309   :mimetype:`rfc822`.
       
   310 
       
   311 :mod:`mimelib` provided some utility functions in its :mod:`address` and
       
   312 :mod:`date` modules.  All of these functions have been moved to the
       
   313 :mod:`email.utils` module.
       
   314 
       
   315 The ``MsgReader`` class/module has been removed.  Its functionality is most
       
   316 closely supported in the :func:`body_line_iterator` function in the
       
   317 :mod:`email.iterators` module.
       
   318 
       
   319 .. rubric:: Footnotes
       
   320 
       
   321 .. [#] Delivery Status Notifications (DSN) are defined in :rfc:`1894`.