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355 lines
16 KiB
ReStructuredText
:mod:`email` --- An email and MIME handling package
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===================================================
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.. module:: email
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:synopsis: Package supporting the parsing, manipulating, and generating
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email messages, including MIME documents.
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.. moduleauthor:: Barry A. Warsaw <barry@python.org>
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.. sectionauthor:: Barry A. Warsaw <barry@python.org>
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.. Copyright (C) 2001-2010 Python Software Foundation
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The :mod:`email` package is a library for managing email messages, including
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MIME and other :rfc:`2822`\ -based message documents. It is specifically *not*
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designed to do any sending of email messages to SMTP (:rfc:`2821`), NNTP, or
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other servers; those are functions of modules such as :mod:`smtplib` and
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:mod:`nntplib`. The :mod:`email` package attempts to be as RFC-compliant as
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possible, supporting in addition to :rfc:`2822`, such MIME-related RFCs as
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:rfc:`2045`, :rfc:`2046`, :rfc:`2047`, and :rfc:`2231`.
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The primary distinguishing feature of the :mod:`email` package is that it splits
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the parsing and generating of email messages from the internal *object model*
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representation of email. Applications using the :mod:`email` package deal
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primarily with objects; you can add sub-objects to messages, remove sub-objects
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from messages, completely re-arrange the contents, etc. There is a separate
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parser and a separate generator which handles the transformation from flat text
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to the object model, and then back to flat text again. There are also handy
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subclasses for some common MIME object types, and a few miscellaneous utilities
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that help with such common tasks as extracting and parsing message field values,
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creating RFC-compliant dates, etc.
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The following sections describe the functionality of the :mod:`email` package.
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The ordering follows a progression that should be common in applications: an
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email message is read as flat text from a file or other source, the text is
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parsed to produce the object structure of the email message, this structure is
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manipulated, and finally, the object tree is rendered back into flat text.
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It is perfectly feasible to create the object structure out of whole cloth ---
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i.e. completely from scratch. From there, a similar progression can be taken as
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above.
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Also included are detailed specifications of all the classes and modules that
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the :mod:`email` package provides, the exception classes you might encounter
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while using the :mod:`email` package, some auxiliary utilities, and a few
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examples. For users of the older :mod:`mimelib` package, or previous versions
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of the :mod:`email` package, a section on differences and porting is provided.
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Contents of the :mod:`email` package documentation:
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.. toctree::
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email.message.rst
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email.parser.rst
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email.generator.rst
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email.mime.rst
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email.header.rst
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email.charset.rst
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email.encoders.rst
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email.errors.rst
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email.util.rst
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email.iterators.rst
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email-examples.rst
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.. seealso::
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Module :mod:`smtplib`
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SMTP protocol client
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Module :mod:`nntplib`
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NNTP protocol client
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.. _email-pkg-history:
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Package History
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---------------
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This table describes the release history of the email package, corresponding to
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the version of Python that the package was released with. For purposes of this
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document, when you see a note about change or added versions, these refer to the
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Python version the change was made in, *not* the email package version. This
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table also describes the Python compatibility of each version of the package.
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+---------------+------------------------------+-----------------------+
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| email version | distributed with | compatible with |
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+===============+==============================+=======================+
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| :const:`1.x` | Python 2.2.0 to Python 2.2.1 | *no longer supported* |
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+---------------+------------------------------+-----------------------+
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| :const:`2.5` | Python 2.2.2+ and Python 2.3 | Python 2.1 to 2.5 |
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+---------------+------------------------------+-----------------------+
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| :const:`3.0` | Python 2.4 | Python 2.3 to 2.5 |
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+---------------+------------------------------+-----------------------+
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| :const:`4.0` | Python 2.5 | Python 2.3 to 2.5 |
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+---------------+------------------------------+-----------------------+
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| :const:`5.0` | Python 3.0 and Python 3.1 | Python 3.0 to 3.2 |
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+---------------+------------------------------+-----------------------+
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| :const:`5.1` | Python 3.2 | Python 3.0 to 3.2 |
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+---------------+------------------------------+-----------------------+
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Here are the major differences between :mod:`email` version 5.1 and
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version 5.0:
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* It is once again possible to parse messages containing non-ASCII bytes,
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and to reproduce such messages if the data containing the non-ASCII
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bytes is not modified.
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* New functions :func:`message_from_bytes` and :func:`message_from_binary_file`,
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and new classes :class:`~email.parser.BytesFeedParser` and
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:class:`~email.parser.BytesParser` allow binary message data to be parsed
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into model objects.
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* Given bytes input to the model, :meth:`~email.message.Message.get_payload`
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will by default decode a message body that has a
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:mailheader:`Content-Transfer-Encoding` of ``8bit`` using the charset
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specified in the MIME headers and return the resulting string.
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* Given bytes input to the model, :class:`~email.generator.Generator` will
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convert message bodies that have a :mailheader:`Content-Transfer-Encoding` of
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8bit to instead have a 7bit Content-Transfer-Encoding.
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* New class :class:`~email.generator.BytesGenerator` produces bytes
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as output, preserving any unchanged non-ASCII data that was
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present in the input used to build the model, including message bodies
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with a :mailheader:`Content-Transfer-Encoding` of 8bit.
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Here are the major differences between :mod:`email` version 5.0 and version 4:
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* All operations are on unicode strings. Text inputs must be strings,
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text outputs are strings. Outputs are limited to the ASCII character
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set and so can be encoded to ASCII for transmission. Inputs are also
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limited to ASCII; this is an acknowledged limitation of email 5.0 and
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means it can only be used to parse email that is 7bit clean.
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Here are the major differences between :mod:`email` version 4 and version 3:
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* All modules have been renamed according to :pep:`8` standards. For example,
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the version 3 module :mod:`email.Message` was renamed to :mod:`email.message` in
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version 4.
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* A new subpackage :mod:`email.mime` was added and all the version 3
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:mod:`email.MIME\*` modules were renamed and situated into the :mod:`email.mime`
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subpackage. For example, the version 3 module :mod:`email.MIMEText` was renamed
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to :mod:`email.mime.text`.
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*Note that the version 3 names will continue to work until Python 2.6*.
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* The :mod:`email.mime.application` module was added, which contains the
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:class:`MIMEApplication` class.
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* Methods that were deprecated in version 3 have been removed. These include
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:meth:`Generator.__call__`, :meth:`Message.get_type`,
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:meth:`Message.get_main_type`, :meth:`Message.get_subtype`.
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* Fixes have been added for :rfc:`2231` support which can change some of the
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return types for :func:`Message.get_param` and friends. Under some
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circumstances, values which used to return a 3-tuple now return simple strings
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(specifically, if all extended parameter segments were unencoded, there is no
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language and charset designation expected, so the return type is now a simple
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string). Also, %-decoding used to be done for both encoded and unencoded
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segments; this decoding is now done only for encoded segments.
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Here are the major differences between :mod:`email` version 3 and version 2:
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* The :class:`FeedParser` class was introduced, and the :class:`Parser` class
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was implemented in terms of the :class:`FeedParser`. All parsing therefore is
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non-strict, and parsing will make a best effort never to raise an exception.
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Problems found while parsing messages are stored in the message's *defect*
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attribute.
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* All aspects of the API which raised :exc:`DeprecationWarning`\ s in version 2
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have been removed. These include the *_encoder* argument to the
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:class:`MIMEText` constructor, the :meth:`Message.add_payload` method, the
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:func:`Utils.dump_address_pair` function, and the functions :func:`Utils.decode`
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and :func:`Utils.encode`.
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* New :exc:`DeprecationWarning`\ s have been added to:
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:meth:`Generator.__call__`, :meth:`Message.get_type`,
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:meth:`Message.get_main_type`, :meth:`Message.get_subtype`, and the *strict*
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argument to the :class:`Parser` class. These are expected to be removed in
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future versions.
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* Support for Pythons earlier than 2.3 has been removed.
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Here are the differences between :mod:`email` version 2 and version 1:
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* The :mod:`email.Header` and :mod:`email.Charset` modules have been added.
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* The pickle format for :class:`Message` instances has changed. Since this was
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never (and still isn't) formally defined, this isn't considered a backward
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incompatibility. However if your application pickles and unpickles
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:class:`Message` instances, be aware that in :mod:`email` version 2,
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:class:`Message` instances now have private variables *_charset* and
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*_default_type*.
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* Several methods in the :class:`Message` class have been deprecated, or their
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signatures changed. Also, many new methods have been added. See the
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documentation for the :class:`Message` class for details. The changes should be
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completely backward compatible.
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* The object structure has changed in the face of :mimetype:`message/rfc822`
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content types. In :mod:`email` version 1, such a type would be represented by a
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scalar payload, i.e. the container message's :meth:`is_multipart` returned
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false, :meth:`get_payload` was not a list object, but a single :class:`Message`
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instance.
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This structure was inconsistent with the rest of the package, so the object
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representation for :mimetype:`message/rfc822` content types was changed. In
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:mod:`email` version 2, the container *does* return ``True`` from
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:meth:`is_multipart`, and :meth:`get_payload` returns a list containing a single
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:class:`Message` item.
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Note that this is one place that backward compatibility could not be completely
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maintained. However, if you're already testing the return type of
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:meth:`get_payload`, you should be fine. You just need to make sure your code
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doesn't do a :meth:`set_payload` with a :class:`Message` instance on a container
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with a content type of :mimetype:`message/rfc822`.
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* The :class:`Parser` constructor's *strict* argument was added, and its
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:meth:`parse` and :meth:`parsestr` methods grew a *headersonly* argument. The
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*strict* flag was also added to functions :func:`email.message_from_file` and
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:func:`email.message_from_string`.
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* :meth:`Generator.__call__` is deprecated; use :meth:`Generator.flatten`
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instead. The :class:`Generator` class has also grown the :meth:`clone` method.
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* The :class:`DecodedGenerator` class in the :mod:`email.Generator` module was
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added.
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* The intermediate base classes :class:`MIMENonMultipart` and
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:class:`MIMEMultipart` have been added, and interposed in the class hierarchy
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for most of the other MIME-related derived classes.
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* The *_encoder* argument to the :class:`MIMEText` constructor has been
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deprecated. Encoding now happens implicitly based on the *_charset* argument.
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* The following functions in the :mod:`email.Utils` module have been deprecated:
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:func:`dump_address_pairs`, :func:`decode`, and :func:`encode`. The following
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functions have been added to the module: :func:`make_msgid`,
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:func:`decode_rfc2231`, :func:`encode_rfc2231`, and :func:`decode_params`.
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* The non-public function :func:`email.Iterators._structure` was added.
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Differences from :mod:`mimelib`
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-------------------------------
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The :mod:`email` package was originally prototyped as a separate library called
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`mimelib <http://mimelib.sf.net/>`_. Changes have been made so that method names
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are more consistent, and some methods or modules have either been added or
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removed. The semantics of some of the methods have also changed. For the most
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part, any functionality available in :mod:`mimelib` is still available in the
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:mod:`email` package, albeit often in a different way. Backward compatibility
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between the :mod:`mimelib` package and the :mod:`email` package was not a
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priority.
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Here is a brief description of the differences between the :mod:`mimelib` and
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the :mod:`email` packages, along with hints on how to port your applications.
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Of course, the most visible difference between the two packages is that the
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package name has been changed to :mod:`email`. In addition, the top-level
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package has the following differences:
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* :func:`messageFromString` has been renamed to :func:`message_from_string`.
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* :func:`messageFromFile` has been renamed to :func:`message_from_file`.
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The :class:`Message` class has the following differences:
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* The method :meth:`asString` was renamed to :meth:`as_string`.
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* The method :meth:`ismultipart` was renamed to :meth:`is_multipart`.
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* The :meth:`get_payload` method has grown a *decode* optional argument.
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* The method :meth:`getall` was renamed to :meth:`get_all`.
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* The method :meth:`addheader` was renamed to :meth:`add_header`.
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* The method :meth:`gettype` was renamed to :meth:`get_type`.
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* The method :meth:`getmaintype` was renamed to :meth:`get_main_type`.
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* The method :meth:`getsubtype` was renamed to :meth:`get_subtype`.
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* The method :meth:`getparams` was renamed to :meth:`get_params`. Also, whereas
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:meth:`getparams` returned a list of strings, :meth:`get_params` returns a list
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of 2-tuples, effectively the key/value pairs of the parameters, split on the
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``'='`` sign.
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* The method :meth:`getparam` was renamed to :meth:`get_param`.
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* The method :meth:`getcharsets` was renamed to :meth:`get_charsets`.
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* The method :meth:`getfilename` was renamed to :meth:`get_filename`.
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* The method :meth:`getboundary` was renamed to :meth:`get_boundary`.
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* The method :meth:`setboundary` was renamed to :meth:`set_boundary`.
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* The method :meth:`getdecodedpayload` was removed. To get similar
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functionality, pass the value 1 to the *decode* flag of the get_payload()
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method.
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* The method :meth:`getpayloadastext` was removed. Similar functionality is
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supported by the :class:`DecodedGenerator` class in the :mod:`email.generator`
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module.
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* The method :meth:`getbodyastext` was removed. You can get similar
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functionality by creating an iterator with :func:`typed_subpart_iterator` in the
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:mod:`email.iterators` module.
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The :class:`Parser` class has no differences in its public interface. It does
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have some additional smarts to recognize :mimetype:`message/delivery-status`
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type messages, which it represents as a :class:`Message` instance containing
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separate :class:`Message` subparts for each header block in the delivery status
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notification [#]_.
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The :class:`Generator` class has no differences in its public interface. There
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is a new class in the :mod:`email.generator` module though, called
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:class:`DecodedGenerator` which provides most of the functionality previously
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available in the :meth:`Message.getpayloadastext` method.
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The following modules and classes have been changed:
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* The :class:`MIMEBase` class constructor arguments *_major* and *_minor* have
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changed to *_maintype* and *_subtype* respectively.
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* The ``Image`` class/module has been renamed to ``MIMEImage``. The *_minor*
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argument has been renamed to *_subtype*.
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* The ``Text`` class/module has been renamed to ``MIMEText``. The *_minor*
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argument has been renamed to *_subtype*.
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* The ``MessageRFC822`` class/module has been renamed to ``MIMEMessage``. Note
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that an earlier version of :mod:`mimelib` called this class/module ``RFC822``,
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but that clashed with the Python standard library module :mod:`rfc822` on some
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case-insensitive file systems.
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Also, the :class:`MIMEMessage` class now represents any kind of MIME message
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with main type :mimetype:`message`. It takes an optional argument *_subtype*
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which is used to set the MIME subtype. *_subtype* defaults to
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:mimetype:`rfc822`.
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:mod:`mimelib` provided some utility functions in its :mod:`address` and
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:mod:`date` modules. All of these functions have been moved to the
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:mod:`email.utils` module.
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The ``MsgReader`` class/module has been removed. Its functionality is most
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closely supported in the :func:`body_line_iterator` function in the
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:mod:`email.iterators` module.
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.. rubric:: Footnotes
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.. [#] Delivery Status Notifications (DSN) are defined in :rfc:`1894`.
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