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| :mod:`email` --- An email and MIME handling package
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| ===================================================
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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.
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| .. moduleauthor:: Barry A. Warsaw <barry@python.org>,
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|                   R. David Murray <rdmurray@bitdance.com>
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| .. sectionauthor:: R. David Murray <rdmurray@bitdance.com>
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| 
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| **Source code:** :source:`Lib/email/__init__.py`
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| 
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| --------------
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| 
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| The :mod:`email` package is a library for managing email messages.  It is
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| specifically *not* designed to do any sending of email messages to SMTP
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| (:rfc:`2821`), NNTP, or other servers; those are functions of modules such as
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| :mod:`smtplib` and :mod:`nntplib`.  The :mod:`email` package attempts to be as
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| RFC-compliant as possible, supporting :rfc:`5322` and :rfc:`6532`, as well as
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| such MIME-related RFCs as :rfc:`2045`, :rfc:`2046`, :rfc:`2047`, :rfc:`2183`,
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| and :rfc:`2231`.
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| 
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| The overall structure of the email package can be divided into three major
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| components, plus a fourth component that controls the behavior of the other
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| components.
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| 
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| The central component of the package is an "object model" that represents email
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| messages.  An application interacts with the package primarily through the
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| object model interface defined in the :mod:`~email.message` sub-module.  The
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| application can use this API to ask questions about an existing email, to
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| construct a new email, or to add or remove email subcomponents that themselves
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| use the same object model interface.  That is, following the nature of email
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| messages and their MIME subcomponents, the email object model is a tree
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| structure of objects that all provide the :class:`~email.message.EmailMessage`
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| API.
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| 
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| The other two major components of the package are the :mod:`~email.parser` and
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| the :mod:`~email.generator`.  The parser takes the serialized version of an
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| email message (a stream of bytes) and converts it into a tree of
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| :class:`~email.message.EmailMessage` objects.  The generator takes an
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| :class:`~email.message.EmailMessage` and turns it back into a serialized byte
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| stream.  (The parser and generator also handle streams of text characters, but
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| this usage is discouraged as it is too easy to end up with messages that are
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| not valid in one way or another.)
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| 
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| The control component is the :mod:`~email.policy` module.  Every
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| :class:`~email.message.EmailMessage`, every :mod:`~email.generator`, and every
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| :mod:`~email.parser` has an associated :mod:`~email.policy` object that
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| controls its behavior.  Usually an application only needs to specify the policy
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| when an :class:`~email.message.EmailMessage` is created, either by directly
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| instantiating an :class:`~email.message.EmailMessage`  to create a new email,
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| or by parsing an input stream using a :mod:`~email.parser`.  But the policy can
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| be changed when the message is serialized using a :mod:`~email.generator`.
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| This allows, for example, a generic email message to be parsed from disk, but
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| to serialize it using standard SMTP settings when sending it to an email
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| server.
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| 
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| The email package does its best to hide the details of the various governing
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| RFCs from the application.  Conceptually the application should be able to
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| treat the email message as a structured tree of unicode text and binary
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| attachments, without having to worry about how these are represented when
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| serialized.  In practice, however, it is often necessary to be aware of at
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| least some of the rules governing MIME messages and their structure,
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| specifically the names and nature of the MIME "content types" and how they
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| identify multipart documents.  For the most part this knowledge should only be
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| required for more complex applications, and even then it should only be the
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| high level structure in question, and not the details of how those structures
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| are represented.  Since MIME content types are used widely in modern internet
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| software (not just email), this will be a familiar concept to many programmers.
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| 
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| The following sections describe the functionality of the :mod:`email` package.
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| We start with the :mod:`~email.message` object model, which is the primary
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| interface an application will use, and follow that with the
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| :mod:`~email.parser` and :mod:`~email.generator` components.  Then we cover the
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| :mod:`~email.policy` controls, which completes the treatment of the main
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| components of the library.
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| 
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| The next three sections cover the exceptions the package may raise and the
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| defects (non-compliance with the RFCs) that the :mod:`~email.parser` may
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| detect.  Then we cover the :mod:`~email.headerregistry` and the
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| :mod:`~email.contentmanager` sub-components, which provide tools for doing more
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| detailed manipulation of headers and payloads, respectively.  Both of these
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| components contain features relevant to consuming and producing non-trivial
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| messages, but also document their extensibility APIs, which will be of interest
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| to advanced applications.
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| 
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| Following those is a set of examples of using the fundamental parts of the APIs
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| covered in the preceding sections.
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| 
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| The foregoing represent the modern (unicode friendly) API of the email package.
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| The remaining sections, starting with the :class:`~email.message.Message`
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| class, cover the legacy :data:`~email.policy.compat32` API that deals much more
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| directly with the details of how email messages are represented.  The
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| :data:`~email.policy.compat32` API does *not* hide the details of the RFCs from
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| the application, but for applications that need to operate at that level, they
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| can be useful tools.  This documentation is also relevant for applications that
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| are still using the :mod:`~email.policy.compat32` API for backward
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| compatibility reasons.
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| 
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| .. versionchanged:: 3.6
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|    Docs reorganized and rewritten to promote the new
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|    :class:`~email.message.EmailMessage`/:class:`~email.policy.EmailPolicy`
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|    API.
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| 
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| Contents of the :mod:`email` package documentation:
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| 
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| .. toctree::
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| 
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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.policy.rst
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| 
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|    email.errors.rst
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|    email.headerregistry.rst
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|    email.contentmanager.rst
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| 
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|    email.examples.rst
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| 
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| Legacy API:
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| 
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| .. toctree::
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| 
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|    email.compat32-message.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.utils.rst
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|    email.iterators.rst
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| 
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| 
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| .. seealso::
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| 
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|    Module :mod:`smtplib`
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|       SMTP (Simple Mail Transport Protocol) client
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| 
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|    Module :mod:`poplib`
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|       POP (Post Office Protocol) client
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| 
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|    Module :mod:`imaplib`
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|       IMAP (Internet Message Access Protocol) client
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| 
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|    Module :mod:`nntplib`
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|       NNTP (Net News Transport Protocol) client
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| 
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|    Module :mod:`mailbox`
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|       Tools for creating, reading, and managing collections of messages on disk
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|       using a variety standard formats.
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| 
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|    Module :mod:`smtpd`
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|       SMTP server framework (primarily useful for testing)
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