:mod:`email` --- An email and MIME handling package

===================================================

.. module:: email

   :synopsis: Package supporting the parsing, manipulating, and generating email messages,

              including MIME documents.

.. moduleauthor:: Barry A. Warsaw <barry@python.org>

.. sectionauthor:: Barry A. Warsaw <barry@python.org>

.. Copyright (C) 2001-2007 Python Software Foundation

.. versionadded:: 2.2

The :mod:`email` package is a library for managing email messages, including

MIME and other :rfc:`2822`\ -based message documents.  It subsumes most of the

functionality in several older standard modules such as :mod:`rfc822`,

:mod:`mimetools`, :mod:`multifile`, and other non-standard packages such as

:mod:`mimecntl`.  It is specifically *not* designed to do any sending of email

messages to SMTP (:rfc:`2821`), NNTP, or other servers; those are functions of

modules such as :mod:`smtplib` and :mod:`nntplib`. The :mod:`email` package

attempts to be as RFC-compliant as possible, supporting in addition to

:rfc:`2822`, such MIME-related RFCs as :rfc:`2045`, :rfc:`2046`, :rfc:`2047`,

and :rfc:`2231`.

The primary distinguishing feature of the :mod:`email` package is that it splits

the parsing and generating of email messages from the internal *object model*

representation of email.  Applications using the :mod:`email` package deal

primarily with objects; you can add sub-objects to messages, remove sub-objects

from messages, completely re-arrange the contents, etc.  There is a separate

parser and a separate generator which handles the transformation from flat text

to the object model, and then back to flat text again.  There are also handy

subclasses for some common MIME object types, and a few miscellaneous utilities

that help with such common tasks as extracting and parsing message field values,

creating RFC-compliant dates, etc.

The following sections describe the functionality of the :mod:`email` package.

The ordering follows a progression that should be common in applications: an

email message is read as flat text from a file or other source, the text is

parsed to produce the object structure of the email message, this structure is

manipulated, and finally, the object tree is rendered back into flat text.

It is perfectly feasible to create the object structure out of whole cloth ---

i.e. completely from scratch.  From there, a similar progression can be taken as

above.

Also included are detailed specifications of all the classes and modules that

the :mod:`email` package provides, the exception classes you might encounter

while using the :mod:`email` package, some auxiliary utilities, and a few

examples.  For users of the older :mod:`mimelib` package, or previous versions

of the :mod:`email` package, a section on differences and porting is provided.

Contents of the :mod:`email` package documentation:

.. toctree::

   email.message.rst

   email.parser.rst

   email.generator.rst

   email.mime.rst

   email.header.rst

   email.charset.rst

   email.encoders.rst

   email.errors.rst

   email.util.rst

   email.iterators.rst

   email-examples.rst

.. seealso::

   Module :mod:`smtplib`

      SMTP protocol client

   Module :mod:`nntplib`

      NNTP protocol client

.. _email-pkg-history:

Package History

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

This table describes the release history of the email package, corresponding to

the version of Python that the package was released with.  For purposes of this

document, when you see a note about change or added versions, these refer to the

Python version the change was made in, *not* the email package version.  This

table also describes the Python compatibility of each version of the package.

+---------------+------------------------------+-----------------------+

| email version | distributed with             | compatible with       |

+===============+==============================+=======================+

| :const:`1.x`  | Python 2.2.0 to Python 2.2.1 | *no longer supported* |

+---------------+------------------------------+-----------------------+

| :const:`2.5`  | Python 2.2.2+ and Python 2.3 | Python 2.1 to 2.5     |

+---------------+------------------------------+-----------------------+

| :const:`3.0`  | Python 2.4                   | Python 2.3 to 2.5     |

+---------------+------------------------------+-----------------------+

| :const:`4.0`  | Python 2.5                   | Python 2.3 to 2.5     |

+---------------+------------------------------+-----------------------+

Here are the major differences between :mod:`email` version 4 and version 3:

* All modules have been renamed according to :pep:`8` standards.  For example,

  the version 3 module :mod:`email.Message` was renamed to :mod:`email.message` in

  version 4.

* A new subpackage :mod:`email.mime` was added and all the version 3

  :mod:`email.MIME\*` modules were renamed and situated into the :mod:`email.mime`

  subpackage.  For example, the version 3 module :mod:`email.MIMEText` was renamed

  to :mod:`email.mime.text`.

  *Note that the version 3 names will continue to work until Python 2.6*.

* The :mod:`email.mime.application` module was added, which contains the

  :class:`MIMEApplication` class.

* Methods that were deprecated in version 3 have been removed.  These include

  :meth:`Generator.__call__`, :meth:`Message.get_type`,

  :meth:`Message.get_main_type`, :meth:`Message.get_subtype`.

* Fixes have been added for :rfc:`2231` support which can change some of the

  return types for :func:`Message.get_param` and friends.  Under some

  circumstances, values which used to return a 3-tuple now return simple strings

  (specifically, if all extended parameter segments were unencoded, there is no

  language and charset designation expected, so the return type is now a simple

  string).  Also, %-decoding used to be done for both encoded and unencoded

  segments; this decoding is now done only for encoded segments.

Here are the major differences between :mod:`email` version 3 and version 2:

* The :class:`FeedParser` class was introduced, and the :class:`Parser` class

  was implemented in terms of the :class:`FeedParser`.  All parsing therefore is

  non-strict, and parsing will make a best effort never to raise an exception.

  Problems found while parsing messages are stored in the message's *defect*

  attribute.

* All aspects of the API which raised :exc:`DeprecationWarning`\ s in version 2

  have been removed.  These include the *_encoder* argument to the

  :class:`MIMEText` constructor, the :meth:`Message.add_payload` method, the

  :func:`Utils.dump_address_pair` function, and the functions :func:`Utils.decode`

  and :func:`Utils.encode`.

* New :exc:`DeprecationWarning`\ s have been added to:

  :meth:`Generator.__call__`, :meth:`Message.get_type`,

  :meth:`Message.get_main_type`, :meth:`Message.get_subtype`, and the *strict*

  argument to the :class:`Parser` class.  These are expected to be removed in

  future versions.

* Support for Pythons earlier than 2.3 has been removed.

Here are the differences between :mod:`email` version 2 and version 1:

* The :mod:`email.Header` and :mod:`email.Charset` modules have been added.

* The pickle format for :class:`Message` instances has changed. Since this was

  never (and still isn't) formally defined, this isn't considered a backward

  incompatibility.  However if your application pickles and unpickles

  :class:`Message` instances, be aware that in :mod:`email` version 2,

  :class:`Message` instances now have private variables *_charset* and

  *_default_type*.

* Several methods in the :class:`Message` class have been deprecated, or their

  signatures changed.  Also, many new methods have been added.  See the

  documentation for the :class:`Message` class for details.  The changes should be

  completely backward compatible.

* The object structure has changed in the face of :mimetype:`message/rfc822`

  content types.  In :mod:`email` version 1, such a type would be represented by a

  scalar payload, i.e. the container message's :meth:`is_multipart` returned

  false, :meth:`get_payload` was not a list object, but a single :class:`Message`

  instance.

  This structure was inconsistent with the rest of the package, so the object

  representation for :mimetype:`message/rfc822` content types was changed.  In

  :mod:`email` version 2, the container *does* return ``True`` from

  :meth:`is_multipart`, and :meth:`get_payload` returns a list containing a single

  :class:`Message` item.

  Note that this is one place that backward compatibility could not be completely

  maintained.  However, if you're already testing the return type of

  :meth:`get_payload`, you should be fine.  You just need to make sure your code

  doesn't do a :meth:`set_payload` with a :class:`Message` instance on a container

  with a content type of :mimetype:`message/rfc822`.

* The :class:`Parser` constructor's *strict* argument was added, and its

  :meth:`parse` and :meth:`parsestr` methods grew a *headersonly* argument.  The

  *strict* flag was also added to functions :func:`email.message_from_file` and

  :func:`email.message_from_string`.

* :meth:`Generator.__call__` is deprecated; use :meth:`Generator.flatten`

  instead.  The :class:`Generator` class has also grown the :meth:`clone` method.

* The :class:`DecodedGenerator` class in the :mod:`email.Generator` module was

  added.

* The intermediate base classes :class:`MIMENonMultipart` and

  :class:`MIMEMultipart` have been added, and interposed in the class hierarchy

  for most of the other MIME-related derived classes.

* The *_encoder* argument to the :class:`MIMEText` constructor has been

  deprecated.  Encoding  now happens implicitly based on the *_charset* argument.

* The following functions in the :mod:`email.Utils` module have been deprecated:

  :func:`dump_address_pairs`, :func:`decode`, and :func:`encode`.  The following

  functions have been added to the module: :func:`make_msgid`,

  :func:`decode_rfc2231`, :func:`encode_rfc2231`, and :func:`decode_params`.

* The non-public function :func:`email.Iterators._structure` was added.

Differences from :mod:`mimelib`

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

The :mod:`email` package was originally prototyped as a separate library called

`mimelib <http://mimelib.sf.net/>`_. Changes have been made so that method names

are more consistent, and some methods or modules have either been added or

removed.  The semantics of some of the methods have also changed.  For the most

part, any functionality available in :mod:`mimelib` is still available in the

:mod:`email` package, albeit often in a different way.  Backward compatibility

between the :mod:`mimelib` package and the :mod:`email` package was not a

priority.

Here is a brief description of the differences between the :mod:`mimelib` and

the :mod:`email` packages, along with hints on how to port your applications.

Of course, the most visible difference between the two packages is that the

package name has been changed to :mod:`email`.  In addition, the top-level

package has the following differences:

* :func:`messageFromString` has been renamed to :func:`message_from_string`.

* :func:`messageFromFile` has been renamed to :func:`message_from_file`.

The :class:`Message` class has the following differences:

* The method :meth:`asString` was renamed to :meth:`as_string`.

* The method :meth:`ismultipart` was renamed to :meth:`is_multipart`.

* The :meth:`get_payload` method has grown a *decode* optional argument.

* The method :meth:`getall` was renamed to :meth:`get_all`.

* The method :meth:`addheader` was renamed to :meth:`add_header`.

* The method :meth:`gettype` was renamed to :meth:`get_type`.

* The method :meth:`getmaintype` was renamed to :meth:`get_main_type`.

* The method :meth:`getsubtype` was renamed to :meth:`get_subtype`.

* The method :meth:`getparams` was renamed to :meth:`get_params`. Also, whereas

  :meth:`getparams` returned a list of strings, :meth:`get_params` returns a list

  of 2-tuples, effectively the key/value pairs of the parameters, split on the

  ``'='`` sign.

* The method :meth:`getparam` was renamed to :meth:`get_param`.

* The method :meth:`getcharsets` was renamed to :meth:`get_charsets`.

* The method :meth:`getfilename` was renamed to :meth:`get_filename`.

* The method :meth:`getboundary` was renamed to :meth:`get_boundary`.

* The method :meth:`setboundary` was renamed to :meth:`set_boundary`.

* The method :meth:`getdecodedpayload` was removed.  To get similar

  functionality, pass the value 1 to the *decode* flag of the get_payload()

  method.

* The method :meth:`getpayloadastext` was removed.  Similar functionality is

  supported by the :class:`DecodedGenerator` class in the :mod:`email.generator`

  module.

* The method :meth:`getbodyastext` was removed.  You can get similar

  functionality by creating an iterator with :func:`typed_subpart_iterator` in the

  :mod:`email.iterators` module.

The :class:`Parser` class has no differences in its public interface. It does

have some additional smarts to recognize :mimetype:`message/delivery-status`

type messages, which it represents as a :class:`Message` instance containing

separate :class:`Message` subparts for each header block in the delivery status

notification [#]_.

The :class:`Generator` class has no differences in its public interface.  There

is a new class in the :mod:`email.generator` module though, called

:class:`DecodedGenerator` which provides most of the functionality previously

available in the :meth:`Message.getpayloadastext` method.

The following modules and classes have been changed:

* The :class:`MIMEBase` class constructor arguments *_major* and *_minor* have

  changed to *_maintype* and *_subtype* respectively.

* The ``Image`` class/module has been renamed to ``MIMEImage``.  The *_minor*

  argument has been renamed to *_subtype*.

* The ``Text`` class/module has been renamed to ``MIMEText``.  The *_minor*

  argument has been renamed to *_subtype*.

* The ``MessageRFC822`` class/module has been renamed to ``MIMEMessage``.  Note

  that an earlier version of :mod:`mimelib` called this class/module ``RFC822``,

  but that clashed with the Python standard library module :mod:`rfc822` on some

  case-insensitive file systems.

  Also, the :class:`MIMEMessage` class now represents any kind of MIME message

  with main type :mimetype:`message`.  It takes an optional argument *_subtype*

  which is used to set the MIME subtype.  *_subtype* defaults to

  :mimetype:`rfc822`.

:mod:`mimelib` provided some utility functions in its :mod:`address` and

:mod:`date` modules.  All of these functions have been moved to the

:mod:`email.utils` module.

The ``MsgReader`` class/module has been removed.  Its functionality is most

closely supported in the :func:`body_line_iterator` function in the

:mod:`email.iterators` module.

.. rubric:: Footnotes

.. [#] Delivery Status Notifications (DSN) are defined in :rfc:`1894`.