/Doc/library/mailbox.rst
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- :mod:`mailbox` --- Manipulate mailboxes in various formats
- ==========================================================
- .. module:: mailbox
- :synopsis: Manipulate mailboxes in various formats
- .. moduleauthor:: Gregory K. Johnson <gkj@gregorykjohnson.com>
- .. sectionauthor:: Gregory K. Johnson <gkj@gregorykjohnson.com>
- This module defines two classes, :class:`Mailbox` and :class:`Message`, for
- accessing and manipulating on-disk mailboxes and the messages they contain.
- :class:`Mailbox` offers a dictionary-like mapping from keys to messages.
- :class:`Message` extends the :mod:`email.Message` module's :class:`Message`
- class with format-specific state and behavior. Supported mailbox formats are
- Maildir, mbox, MH, Babyl, and MMDF.
- .. seealso::
- Module :mod:`email`
- Represent and manipulate messages.
- .. _mailbox-objects:
- :class:`Mailbox` objects
- ------------------------
- .. class:: Mailbox
- A mailbox, which may be inspected and modified.
- The :class:`Mailbox` class defines an interface and is not intended to be
- instantiated. Instead, format-specific subclasses should inherit from
- :class:`Mailbox` and your code should instantiate a particular subclass.
- The :class:`Mailbox` interface is dictionary-like, with small keys
- corresponding to messages. Keys are issued by the :class:`Mailbox` instance
- with which they will be used and are only meaningful to that :class:`Mailbox`
- instance. A key continues to identify a message even if the corresponding
- message is modified, such as by replacing it with another message.
- Messages may be added to a :class:`Mailbox` instance using the set-like
- method :meth:`add` and removed using a ``del`` statement or the set-like
- methods :meth:`remove` and :meth:`discard`.
- :class:`Mailbox` interface semantics differ from dictionary semantics in some
- noteworthy ways. Each time a message is requested, a new representation
- (typically a :class:`Message` instance) is generated based upon the current
- state of the mailbox. Similarly, when a message is added to a
- :class:`Mailbox` instance, the provided message representation's contents are
- copied. In neither case is a reference to the message representation kept by
- the :class:`Mailbox` instance.
- The default :class:`Mailbox` iterator iterates over message representations,
- not keys as the default dictionary iterator does. Moreover, modification of a
- mailbox during iteration is safe and well-defined. Messages added to the
- mailbox after an iterator is created will not be seen by the
- iterator. Messages removed from the mailbox before the iterator yields them
- will be silently skipped, though using a key from an iterator may result in a
- :exc:`KeyError` exception if the corresponding message is subsequently
- removed.
- .. warning::
- Be very cautious when modifying mailboxes that might be simultaneously
- changed by some other process. The safest mailbox format to use for such
- tasks is Maildir; try to avoid using single-file formats such as mbox for
- concurrent writing. If you're modifying a mailbox, you *must* lock it by
- calling the :meth:`lock` and :meth:`unlock` methods *before* reading any
- messages in the file or making any changes by adding or deleting a
- message. Failing to lock the mailbox runs the risk of losing messages or
- corrupting the entire mailbox.
- :class:`Mailbox` instances have the following methods:
- .. method:: add(message)
- Add *message* to the mailbox and return the key that has been assigned to
- it.
- Parameter *message* may be a :class:`Message` instance, an
- :class:`email.Message.Message` instance, a string, or a file-like object
- (which should be open in text mode). If *message* is an instance of the
- appropriate format-specific :class:`Message` subclass (e.g., if it's an
- :class:`mboxMessage` instance and this is an :class:`mbox` instance), its
- format-specific information is used. Otherwise, reasonable defaults for
- format-specific information are used.
- .. method:: remove(key)
- __delitem__(key)
- discard(key)
- Delete the message corresponding to *key* from the mailbox.
- If no such message exists, a :exc:`KeyError` exception is raised if the
- method was called as :meth:`remove` or :meth:`__delitem__` but no
- exception is raised if the method was called as :meth:`discard`. The
- behavior of :meth:`discard` may be preferred if the underlying mailbox
- format supports concurrent modification by other processes.
- .. method:: __setitem__(key, message)
- Replace the message corresponding to *key* with *message*. Raise a
- :exc:`KeyError` exception if no message already corresponds to *key*.
- As with :meth:`add`, parameter *message* may be a :class:`Message`
- instance, an :class:`email.Message.Message` instance, a string, or a
- file-like object (which should be open in text mode). If *message* is an
- instance of the appropriate format-specific :class:`Message` subclass
- (e.g., if it's an :class:`mboxMessage` instance and this is an
- :class:`mbox` instance), its format-specific information is
- used. Otherwise, the format-specific information of the message that
- currently corresponds to *key* is left unchanged.
- .. method:: iterkeys()
- keys()
- Return an iterator over all keys if called as :meth:`iterkeys` or return a
- list of keys if called as :meth:`keys`.
- .. method:: itervalues()
- __iter__()
- values()
- Return an iterator over representations of all messages if called as
- :meth:`itervalues` or :meth:`__iter__` or return a list of such
- representations if called as :meth:`values`. The messages are represented
- as instances of the appropriate format-specific :class:`Message` subclass
- unless a custom message factory was specified when the :class:`Mailbox`
- instance was initialized.
- .. note::
- The behavior of :meth:`__iter__` is unlike that of dictionaries, which
- iterate over keys.
- .. method:: iteritems()
- items()
- Return an iterator over (*key*, *message*) pairs, where *key* is a key and
- *message* is a message representation, if called as :meth:`iteritems` or
- return a list of such pairs if called as :meth:`items`. The messages are
- represented as instances of the appropriate format-specific
- :class:`Message` subclass unless a custom message factory was specified
- when the :class:`Mailbox` instance was initialized.
- .. method:: get(key[, default=None])
- __getitem__(key)
- Return a representation of the message corresponding to *key*. If no such
- message exists, *default* is returned if the method was called as
- :meth:`get` and a :exc:`KeyError` exception is raised if the method was
- called as :meth:`__getitem__`. The message is represented as an instance
- of the appropriate format-specific :class:`Message` subclass unless a
- custom message factory was specified when the :class:`Mailbox` instance
- was initialized.
- .. method:: get_message(key)
- Return a representation of the message corresponding to *key* as an
- instance of the appropriate format-specific :class:`Message` subclass, or
- raise a :exc:`KeyError` exception if no such message exists.
- .. method:: get_string(key)
- Return a string representation of the message corresponding to *key*, or
- raise a :exc:`KeyError` exception if no such message exists.
- .. method:: get_file(key)
- Return a file-like representation of the message corresponding to *key*,
- or raise a :exc:`KeyError` exception if no such message exists. The
- file-like object behaves as if open in binary mode. This file should be
- closed once it is no longer needed.
- .. note::
- Unlike other representations of messages, file-like representations are
- not necessarily independent of the :class:`Mailbox` instance that
- created them or of the underlying mailbox. More specific documentation
- is provided by each subclass.
- .. method:: has_key(key)
- __contains__(key)
- Return ``True`` if *key* corresponds to a message, ``False`` otherwise.
- .. method:: __len__()
- Return a count of messages in the mailbox.
- .. method:: clear()
- Delete all messages from the mailbox.
- .. method:: pop(key[, default])
- Return a representation of the message corresponding to *key* and delete
- the message. If no such message exists, return *default* if it was
- supplied or else raise a :exc:`KeyError` exception. The message is
- represented as an instance of the appropriate format-specific
- :class:`Message` subclass unless a custom message factory was specified
- when the :class:`Mailbox` instance was initialized.
- .. method:: popitem()
- Return an arbitrary (*key*, *message*) pair, where *key* is a key and
- *message* is a message representation, and delete the corresponding
- message. If the mailbox is empty, raise a :exc:`KeyError` exception. The
- message is represented as an instance of the appropriate format-specific
- :class:`Message` subclass unless a custom message factory was specified
- when the :class:`Mailbox` instance was initialized.
- .. method:: update(arg)
- Parameter *arg* should be a *key*-to-*message* mapping or an iterable of
- (*key*, *message*) pairs. Updates the mailbox so that, for each given
- *key* and *message*, the message corresponding to *key* is set to
- *message* as if by using :meth:`__setitem__`. As with :meth:`__setitem__`,
- each *key* must already correspond to a message in the mailbox or else a
- :exc:`KeyError` exception will be raised, so in general it is incorrect
- for *arg* to be a :class:`Mailbox` instance.
- .. note::
- Unlike with dictionaries, keyword arguments are not supported.
- .. method:: flush()
- Write any pending changes to the filesystem. For some :class:`Mailbox`
- subclasses, changes are always written immediately and :meth:`flush` does
- nothing, but you should still make a habit of calling this method.
- .. method:: lock()
- Acquire an exclusive advisory lock on the mailbox so that other processes
- know not to modify it. An :exc:`ExternalClashError` is raised if the lock
- is not available. The particular locking mechanisms used depend upon the
- mailbox format. You should *always* lock the mailbox before making any
- modifications to its contents.
- .. method:: unlock()
- Release the lock on the mailbox, if any.
- .. method:: close()
- Flush the mailbox, unlock it if necessary, and close any open files. For
- some :class:`Mailbox` subclasses, this method does nothing.
- .. _mailbox-maildir:
- :class:`Maildir`
- ^^^^^^^^^^^^^^^^
- .. class:: Maildir(dirname[, factory=rfc822.Message[, create=True]])
- A subclass of :class:`Mailbox` for mailboxes in Maildir format. Parameter
- *factory* is a callable object that accepts a file-like message representation
- (which behaves as if opened in binary mode) and returns a custom representation.
- If *factory* is ``None``, :class:`MaildirMessage` is used as the default message
- representation. If *create* is ``True``, the mailbox is created if it does not
- exist.
- It is for historical reasons that *factory* defaults to :class:`rfc822.Message`
- and that *dirname* is named as such rather than *path*. For a :class:`Maildir`
- instance that behaves like instances of other :class:`Mailbox` subclasses, set
- *factory* to ``None``.
- Maildir is a directory-based mailbox format invented for the qmail mail
- transfer agent and now widely supported by other programs. Messages in a
- Maildir mailbox are stored in separate files within a common directory
- structure. This design allows Maildir mailboxes to be accessed and modified
- by multiple unrelated programs without data corruption, so file locking is
- unnecessary.
- Maildir mailboxes contain three subdirectories, namely: :file:`tmp`,
- :file:`new`, and :file:`cur`. Messages are created momentarily in the
- :file:`tmp` subdirectory and then moved to the :file:`new` subdirectory to
- finalize delivery. A mail user agent may subsequently move the message to the
- :file:`cur` subdirectory and store information about the state of the message
- in a special "info" section appended to its file name.
- Folders of the style introduced by the Courier mail transfer agent are also
- supported. Any subdirectory of the main mailbox is considered a folder if
- ``'.'`` is the first character in its name. Folder names are represented by
- :class:`Maildir` without the leading ``'.'``. Each folder is itself a Maildir
- mailbox but should not contain other folders. Instead, a logical nesting is
- indicated using ``'.'`` to delimit levels, e.g., "Archived.2005.07".
- .. note::
- The Maildir specification requires the use of a colon (``':'``) in certain
- message file names. However, some operating systems do not permit this
- character in file names, If you wish to use a Maildir-like format on such
- an operating system, you should specify another character to use
- instead. The exclamation point (``'!'``) is a popular choice. For
- example::
- import mailbox
- mailbox.Maildir.colon = '!'
- The :attr:`colon` attribute may also be set on a per-instance basis.
- :class:`Maildir` instances have all of the methods of :class:`Mailbox` in
- addition to the following:
- .. method:: list_folders()
- Return a list of the names of all folders.
- .. method:: get_folder(folder)
- Return a :class:`Maildir` instance representing the folder whose name is
- *folder*. A :exc:`NoSuchMailboxError` exception is raised if the folder
- does not exist.
- .. method:: add_folder(folder)
- Create a folder whose name is *folder* and return a :class:`Maildir`
- instance representing it.
- .. method:: remove_folder(folder)
- Delete the folder whose name is *folder*. If the folder contains any
- messages, a :exc:`NotEmptyError` exception will be raised and the folder
- will not be deleted.
- .. method:: clean()
- Delete temporary files from the mailbox that have not been accessed in the
- last 36 hours. The Maildir specification says that mail-reading programs
- should do this occasionally.
- Some :class:`Mailbox` methods implemented by :class:`Maildir` deserve special
- remarks:
- .. method:: add(message)
- __setitem__(key, message)
- update(arg)
- .. warning::
- These methods generate unique file names based upon the current process
- ID. When using multiple threads, undetected name clashes may occur and
- cause corruption of the mailbox unless threads are coordinated to avoid
- using these methods to manipulate the same mailbox simultaneously.
- .. method:: flush()
- All changes to Maildir mailboxes are immediately applied, so this method
- does nothing.
- .. method:: lock()
- unlock()
- Maildir mailboxes do not support (or require) locking, so these methods do
- nothing.
- .. method:: close()
- :class:`Maildir` instances do not keep any open files and the underlying
- mailboxes do not support locking, so this method does nothing.
- .. method:: get_file(key)
- Depending upon the host platform, it may not be possible to modify or
- remove the underlying message while the returned file remains open.
- .. seealso::
- `maildir man page from qmail <http://www.qmail.org/man/man5/maildir.html>`_
- The original specification of the format.
- `Using maildir format <http://cr.yp.to/proto/maildir.html>`_
- Notes on Maildir by its inventor. Includes an updated name-creation scheme and
- details on "info" semantics.
- `maildir man page from Courier <http://www.courier-mta.org/maildir.html>`_
- Another specification of the format. Describes a common extension for supporting
- folders.
- .. _mailbox-mbox:
- :class:`mbox`
- ^^^^^^^^^^^^^
- .. class:: mbox(path[, factory=None[, create=True]])
- A subclass of :class:`Mailbox` for mailboxes in mbox format. Parameter *factory*
- is a callable object that accepts a file-like message representation (which
- behaves as if opened in binary mode) and returns a custom representation. If
- *factory* is ``None``, :class:`mboxMessage` is used as the default message
- representation. If *create* is ``True``, the mailbox is created if it does not
- exist.
- The mbox format is the classic format for storing mail on Unix systems. All
- messages in an mbox mailbox are stored in a single file with the beginning of
- each message indicated by a line whose first five characters are "From ".
- Several variations of the mbox format exist to address perceived shortcomings in
- the original. In the interest of compatibility, :class:`mbox` implements the
- original format, which is sometimes referred to as :dfn:`mboxo`. This means that
- the :mailheader:`Content-Length` header, if present, is ignored and that any
- occurrences of "From " at the beginning of a line in a message body are
- transformed to ">From " when storing the message, although occurrences of ">From
- " are not transformed to "From " when reading the message.
- Some :class:`Mailbox` methods implemented by :class:`mbox` deserve special
- remarks:
- .. method:: get_file(key)
- Using the file after calling :meth:`flush` or :meth:`close` on the
- :class:`mbox` instance may yield unpredictable results or raise an
- exception.
- .. method:: lock()
- unlock()
- Three locking mechanisms are used---dot locking and, if available, the
- :cfunc:`flock` and :cfunc:`lockf` system calls.
- .. seealso::
- `mbox man page from qmail <http://www.qmail.org/man/man5/mbox.html>`_
- A specification of the format and its variations.
- `mbox man page from tin <http://www.tin.org/bin/man.cgi?section=5&topic=mbox>`_
- Another specification of the format, with details on locking.
- `Configuring Netscape Mail on Unix: Why The Content-Length Format is Bad <http://www.jwz.org/doc/content-length.html>`_
- An argument for using the original mbox format rather than a variation.
- `"mbox" is a family of several mutually incompatible mailbox formats <http://homepages.tesco.net./~J.deBoynePollard/FGA/mail-mbox-formats.html>`_
- A history of mbox variations.
- .. _mailbox-mh:
- :class:`MH`
- ^^^^^^^^^^^
- .. class:: MH(path[, factory=None[, create=True]])
- A subclass of :class:`Mailbox` for mailboxes in MH format. Parameter *factory*
- is a callable object that accepts a file-like message representation (which
- behaves as if opened in binary mode) and returns a custom representation. If
- *factory* is ``None``, :class:`MHMessage` is used as the default message
- representation. If *create* is ``True``, the mailbox is created if it does not
- exist.
- MH is a directory-based mailbox format invented for the MH Message Handling
- System, a mail user agent. Each message in an MH mailbox resides in its own
- file. An MH mailbox may contain other MH mailboxes (called :dfn:`folders`) in
- addition to messages. Folders may be nested indefinitely. MH mailboxes also
- support :dfn:`sequences`, which are named lists used to logically group
- messages without moving them to sub-folders. Sequences are defined in a file
- called :file:`.mh_sequences` in each folder.
- The :class:`MH` class manipulates MH mailboxes, but it does not attempt to
- emulate all of :program:`mh`'s behaviors. In particular, it does not modify
- and is not affected by the :file:`context` or :file:`.mh_profile` files that
- are used by :program:`mh` to store its state and configuration.
- :class:`MH` instances have all of the methods of :class:`Mailbox` in addition
- to the following:
- .. method:: list_folders()
- Return a list of the names of all folders.
- .. method:: get_folder(folder)
- Return an :class:`MH` instance representing the folder whose name is
- *folder*. A :exc:`NoSuchMailboxError` exception is raised if the folder
- does not exist.
- .. method:: add_folder(folder)
- Create a folder whose name is *folder* and return an :class:`MH` instance
- representing it.
- .. method:: remove_folder(folder)
- Delete the folder whose name is *folder*. If the folder contains any
- messages, a :exc:`NotEmptyError` exception will be raised and the folder
- will not be deleted.
- .. method:: get_sequences()
- Return a dictionary of sequence names mapped to key lists. If there are no
- sequences, the empty dictionary is returned.
- .. method:: set_sequences(sequences)
- Re-define the sequences that exist in the mailbox based upon *sequences*,
- a dictionary of names mapped to key lists, like returned by
- :meth:`get_sequences`.
- .. method:: pack()
- Rename messages in the mailbox as necessary to eliminate gaps in
- numbering. Entries in the sequences list are updated correspondingly.
- .. note::
- Already-issued keys are invalidated by this operation and should not be
- subsequently used.
- Some :class:`Mailbox` methods implemented by :class:`MH` deserve special
- remarks:
- .. method:: remove(key)
- __delitem__(key)
- discard(key)
- These methods immediately delete the message. The MH convention of marking
- a message for deletion by prepending a comma to its name is not used.
- .. method:: lock()
- unlock()
- Three locking mechanisms are used---dot locking and, if available, the
- :cfunc:`flock` and :cfunc:`lockf` system calls. For MH mailboxes, locking
- the mailbox means locking the :file:`.mh_sequences` file and, only for the
- duration of any operations that affect them, locking individual message
- files.
- .. method:: get_file(key)
- Depending upon the host platform, it may not be possible to remove the
- underlying message while the returned file remains open.
- .. method:: flush()
- All changes to MH mailboxes are immediately applied, so this method does
- nothing.
- .. method:: close()
- :class:`MH` instances do not keep any open files, so this method is
- equivalent to :meth:`unlock`.
- .. seealso::
- `nmh - Message Handling System <http://www.nongnu.org/nmh/>`_
- Home page of :program:`nmh`, an updated version of the original :program:`mh`.
- `MH & nmh: Email for Users & Programmers <http://www.ics.uci.edu/~mh/book/>`_
- A GPL-licensed book on :program:`mh` and :program:`nmh`, with some information
- on the mailbox format.
- .. _mailbox-babyl:
- :class:`Babyl`
- ^^^^^^^^^^^^^^
- .. class:: Babyl(path[, factory=None[, create=True]])
- A subclass of :class:`Mailbox` for mailboxes in Babyl format. Parameter
- *factory* is a callable object that accepts a file-like message representation
- (which behaves as if opened in binary mode) and returns a custom representation.
- If *factory* is ``None``, :class:`BabylMessage` is used as the default message
- representation. If *create* is ``True``, the mailbox is created if it does not
- exist.
- Babyl is a single-file mailbox format used by the Rmail mail user agent
- included with Emacs. The beginning of a message is indicated by a line
- containing the two characters Control-Underscore (``'\037'``) and Control-L
- (``'\014'``). The end of a message is indicated by the start of the next
- message or, in the case of the last message, a line containing a
- Control-Underscore (``'\037'``) character.
- Messages in a Babyl mailbox have two sets of headers, original headers and
- so-called visible headers. Visible headers are typically a subset of the
- original headers that have been reformatted or abridged to be more
- attractive. Each message in a Babyl mailbox also has an accompanying list of
- :dfn:`labels`, or short strings that record extra information about the
- message, and a list of all user-defined labels found in the mailbox is kept
- in the Babyl options section.
- :class:`Babyl` instances have all of the methods of :class:`Mailbox` in
- addition to the following:
- .. method:: get_labels()
- Return a list of the names of all user-defined labels used in the mailbox.
- .. note::
- The actual messages are inspected to determine which labels exist in
- the mailbox rather than consulting the list of labels in the Babyl
- options section, but the Babyl section is updated whenever the mailbox
- is modified.
- Some :class:`Mailbox` methods implemented by :class:`Babyl` deserve special
- remarks:
- .. method:: get_file(key)
- In Babyl mailboxes, the headers of a message are not stored contiguously
- with the body of the message. To generate a file-like representation, the
- headers and body are copied together into a :class:`StringIO` instance
- (from the :mod:`StringIO` module), which has an API identical to that of a
- file. As a result, the file-like object is truly independent of the
- underlying mailbox but does not save memory compared to a string
- representation.
- .. method:: lock()
- unlock()
- Three locking mechanisms are used---dot locking and, if available, the
- :cfunc:`flock` and :cfunc:`lockf` system calls.
- .. seealso::
- `Format of Version 5 Babyl Files <http://quimby.gnus.org/notes/BABYL>`_
- A specification of the Babyl format.
- `Reading Mail with Rmail <http://www.gnu.org/software/emacs/manual/html_node/emacs/Rmail.html>`_
- The Rmail manual, with some information on Babyl semantics.
- .. _mailbox-mmdf:
- :class:`MMDF`
- ^^^^^^^^^^^^^
- .. class:: MMDF(path[, factory=None[, create=True]])
- A subclass of :class:`Mailbox` for mailboxes in MMDF format. Parameter *factory*
- is a callable object that accepts a file-like message representation (which
- behaves as if opened in binary mode) and returns a custom representation. If
- *factory* is ``None``, :class:`MMDFMessage` is used as the default message
- representation. If *create* is ``True``, the mailbox is created if it does not
- exist.
- MMDF is a single-file mailbox format invented for the Multichannel Memorandum
- Distribution Facility, a mail transfer agent. Each message is in the same
- form as an mbox message but is bracketed before and after by lines containing
- four Control-A (``'\001'``) characters. As with the mbox format, the
- beginning of each message is indicated by a line whose first five characters
- are "From ", but additional occurrences of "From " are not transformed to
- ">From " when storing messages because the extra message separator lines
- prevent mistaking such occurrences for the starts of subsequent messages.
- Some :class:`Mailbox` methods implemented by :class:`MMDF` deserve special
- remarks:
- .. method:: get_file(key)
- Using the file after calling :meth:`flush` or :meth:`close` on the
- :class:`MMDF` instance may yield unpredictable results or raise an
- exception.
- .. method:: lock()
- unlock()
- Three locking mechanisms are used---dot locking and, if available, the
- :cfunc:`flock` and :cfunc:`lockf` system calls.
- .. seealso::
- `mmdf man page from tin <http://www.tin.org/bin/man.cgi?section=5&topic=mmdf>`_
- A specification of MMDF format from the documentation of tin, a newsreader.
- `MMDF <http://en.wikipedia.org/wiki/MMDF>`_
- A Wikipedia article describing the Multichannel Memorandum Distribution
- Facility.
- .. _mailbox-message-objects:
- :class:`Message` objects
- ------------------------
- .. class:: Message([message])
- A subclass of the :mod:`email.Message` module's :class:`Message`. Subclasses of
- :class:`mailbox.Message` add mailbox-format-specific state and behavior.
- If *message* is omitted, the new instance is created in a default, empty state.
- If *message* is an :class:`email.Message.Message` instance, its contents are
- copied; furthermore, any format-specific information is converted insofar as
- possible if *message* is a :class:`Message` instance. If *message* is a string
- or a file, it should contain an :rfc:`2822`\ -compliant message, which is read
- and parsed.
- The format-specific state and behaviors offered by subclasses vary, but in
- general it is only the properties that are not specific to a particular
- mailbox that are supported (although presumably the properties are specific
- to a particular mailbox format). For example, file offsets for single-file
- mailbox formats and file names for directory-based mailbox formats are not
- retained, because they are only applicable to the original mailbox. But state
- such as whether a message has been read by the user or marked as important is
- retained, because it applies to the message itself.
- There is no requirement that :class:`Message` instances be used to represent
- messages retrieved using :class:`Mailbox` instances. In some situations, the
- time and memory required to generate :class:`Message` representations might
- not not acceptable. For such situations, :class:`Mailbox` instances also
- offer string and file-like representations, and a custom message factory may
- be specified when a :class:`Mailbox` instance is initialized.
- .. _mailbox-maildirmessage:
- :class:`MaildirMessage`
- ^^^^^^^^^^^^^^^^^^^^^^^
- .. class:: MaildirMessage([message])
- A message with Maildir-specific behaviors. Parameter *message* has the same
- meaning as with the :class:`Message` constructor.
- Typically, a mail user agent application moves all of the messages in the
- :file:`new` subdirectory to the :file:`cur` subdirectory after the first time
- the user opens and closes the mailbox, recording that the messages are old
- whether or not they've actually been read. Each message in :file:`cur` has an
- "info" section added to its file name to store information about its state.
- (Some mail readers may also add an "info" section to messages in
- :file:`new`.) The "info" section may take one of two forms: it may contain
- "2," followed by a list of standardized flags (e.g., "2,FR") or it may
- contain "1," followed by so-called experimental information. Standard flags
- for Maildir messages are as follows:
- +------+---------+--------------------------------+
- | Flag | Meaning | Explanation |
- +======+=========+================================+
- | D | Draft | Under composition |
- +------+---------+--------------------------------+
- | F | Flagged | Marked as important |
- +------+---------+--------------------------------+
- | P | Passed | Forwarded, resent, or bounced |
- +------+---------+--------------------------------+
- | R | Replied | Replied to |
- +------+---------+--------------------------------+
- | S | Seen | Read |
- +------+---------+--------------------------------+
- | T | Trashed | Marked for subsequent deletion |
- +------+---------+--------------------------------+
- :class:`MaildirMessage` instances offer the following methods:
- .. method:: get_subdir()
- Return either "new" (if the message should be stored in the :file:`new`
- subdirectory) or "cur" (if the message should be stored in the :file:`cur`
- subdirectory).
- .. note::
- A message is typically moved from :file:`new` to :file:`cur` after its
- mailbox has been accessed, whether or not the message is has been
- read. A message ``msg`` has been read if ``"S" in msg.get_flags()`` is
- ``True``.
- .. method:: set_subdir(subdir)
- Set the subdirectory the message should be stored in. Parameter *subdir*
- must be either "new" or "cur".
- .. method:: get_flags()
- Return a string specifying the flags that are currently set. If the
- message complies with the standard Maildir format, the result is the
- concatenation in alphabetical order of zero or one occurrence of each of
- ``'D'``, ``'F'``, ``'P'``, ``'R'``, ``'S'``, and ``'T'``. The empty string
- is returned if no flags are set or if "info" contains experimental
- semantics.
- .. method:: set_flags(flags)
- Set the flags specified by *flags* and unset all others.
- .. method:: add_flag(flag)
- Set the flag(s) specified by *flag* without changing other flags. To add
- more than one flag at a time, *flag* may be a string of more than one
- character. The current "info" is overwritten whether or not it contains
- experimental information rather than flags.
- .. method:: remove_flag(flag)
- Unset the flag(s) specified by *flag* without changing other flags. To
- remove more than one flag at a time, *flag* maybe a string of more than
- one character. If "info" contains experimental information rather than
- flags, the current "info" is not modified.
- .. method:: get_date()
- Return the delivery date of the message as a floating-point number
- representing seconds since the epoch.
- .. method:: set_date(date)
- Set the delivery date of the message to *date*, a floating-point number
- representing seconds since the epoch.
- .. method:: get_info()
- Return a string containing the "info" for a message. This is useful for
- accessing and modifying "info" that is experimental (i.e., not a list of
- flags).
- .. method:: set_info(info)
- Set "info" to *info*, which should be a string.
- When a :class:`MaildirMessage` instance is created based upon an
- :class:`mboxMessage` or :class:`MMDFMessage` instance, the :mailheader:`Status`
- and :mailheader:`X-Status` headers are omitted and the following conversions
- take place:
- +--------------------+----------------------------------------------+
- | Resulting state | :class:`mboxMessage` or :class:`MMDFMessage` |
- | | state |
- +====================+==============================================+
- | "cur" subdirectory | O flag |
- +--------------------+----------------------------------------------+
- | F flag | F flag |
- +--------------------+----------------------------------------------+
- | R flag | A flag |
- +--------------------+----------------------------------------------+
- | S flag | R flag |
- +--------------------+----------------------------------------------+
- | T flag | D flag |
- +--------------------+----------------------------------------------+
- When a :class:`MaildirMessage` instance is created based upon an
- :class:`MHMessage` instance, the following conversions take place:
- +-------------------------------+--------------------------+
- | Resulting state | :class:`MHMessage` state |
- +===============================+==========================+
- | "cur" subdirectory | "unseen" sequence |
- +-------------------------------+--------------------------+
- | "cur" subdirectory and S flag | no "unseen" sequence |
- +-------------------------------+--------------------------+
- | F flag | "flagged" sequence |
- +-------------------------------+--------------------------+
- | R flag | "replied" sequence |
- +-------------------------------+--------------------------+
- When a :class:`MaildirMessage` instance is created based upon a
- :class:`BabylMessage` instance, the following conversions take place:
- +-------------------------------+-------------------------------+
- | Resulting state | :class:`BabylMessage` state |
- +===============================+===============================+
- | "cur" subdirectory | "unseen" label |
- +-------------------------------+-------------------------------+
- | "cur" subdirectory and S flag | no "unseen" label |
- +-------------------------------+-------------------------------+
- | P flag | "forwarded" or "resent" label |
- +-------------------------------+-------------------------------+
- | R flag | "answered" label |
- +-------------------------------+-------------------------------+
- | T flag | "deleted" label |
- +-------------------------------+-------------------------------+
- .. _mailbox-mboxmessage:
- :class:`mboxMessage`
- ^^^^^^^^^^^^^^^^^^^^
- .. class:: mboxMessage([message])
- A message with mbox-specific behaviors. Parameter *message* has the same meaning
- as with the :class:`Message` constructor.
- Messages in an mbox mailbox are stored together in a single file. The
- sender's envelope address and the time of delivery are typically stored in a
- line beginning with "From " that is used to indicate the start of a message,
- though there is considerable variation in the exact format of this data among
- mbox implementations. Flags that indicate the state of the message, such as
- whether it has been read or marked as important, are typically stored in
- :mailheader:`Status` and :mailheader:`X-Status` headers.
- Conventional flags for mbox messages are as follows:
- +------+----------+--------------------------------+
- | Flag | Meaning | Explanation |
- +======+==========+================================+
- | R | Read | Read |
- +------+----------+--------------------------------+
- | O | Old | Previously detected by MUA |
- +------+----------+--------------------------------+
- | D | Deleted | Marked for subsequent deletion |
- +------+----------+--------------------------------+
- | F | Flagged | Marked as important |
- +------+----------+--------------------------------+
- | A | Answered | Replied to |
- +------+----------+--------------------------------+
- The "R" and "O" flags are stored in the :mailheader:`Status` header, and the
- "D", "F", and "A" flags are stored in the :mailheader:`X-Status` header. The
- flags and headers typically appear in the order mentioned.
- :class:`mboxMessage` instances offer the following methods:
- .. method:: get_from()
- Return a string representing the "From " line that marks the start of the
- message in an mbox mailbox. The leading "From " and the trailing newline
- are excluded.
- .. method:: set_from(from_[, time_=None])
- Set the "From " line to *from_*, which should be specified without a
- leading "From " or trailing newline. For convenience, *time_* may be
- specified and will be formatted appropriately and appended to *from_*. If
- *time_* is specified, it should be a :class:`struct_time` instance, a
- tuple suitable for passing to :meth:`time.strftime`, or ``True`` (to use
- :meth:`time.gmtime`).
- .. method:: get_flags()
- Return a string specifying the flags that are currently set. If the
- message complies with the conventional format, the result is the
- concatenation in the following order of zero or one occurrence of each of
- ``'R'``, ``'O'``, ``'D'``, ``'F'``, and ``'A'``.
- .. method:: set_flags(flags)
- Set the flags specified by *flags* and unset all others. Parameter *flags*
- should be the concatenation in any order of zero or more occurrences of
- each of ``'R'``, ``'O'``, ``'D'``, ``'F'``, and ``'A'``.
- .. method:: add_flag(flag)
- Set the flag(s) specified by *flag* without changing other flags. To add
- more than one flag at a time, *flag* may be a string of more than one
- character.
- .. method:: remove_flag(flag)
- Unset the flag(s) specified by *flag* without changing other flags. To
- remove more than one flag at a time, *flag* maybe a string of more than
- one character.
- When an :class:`mboxMessage` instance is created based upon a
- :class:`MaildirMessage` instance, a "From " line is generated based upon the
- :class:`MaildirMessage` instance's delivery date, and the following conversions
- take place:
- +-----------------+-------------------------------+
- | Resulting state | :class:`MaildirMessage` state |
- +=================+===============================+
- | R flag | S flag |
- +-----------------+-------------------------------+
- | O flag | "cur" subdirectory |
- +-----------------+-------------------------------+
- | D flag | T flag |
- +-----------------+-------------------------------+
- | F flag | F flag |
- +-----------------+-------------------------------+
- | A flag | R flag |
- +-----------------+-------------------------------+
- When an :class:`mboxMessage` instance is created based upon an
- :class:`MHMessage` instance, the following conversions take place:
- +-------------------+--------------------------+
- | Resulting state | :class:`MHMessage` state |
- +===================+==========================+
- | R flag and O flag | no "unseen" sequence |
- +-------------------+--------------------------+
- | O flag | "unseen" sequence |
- +-------------------+--------------------------+
- | F flag | "flagged" sequence |
- +-------------------+--------------------------+
- | A flag | "replied" sequence |
- +-------------------+--------------------------+
- When an :class:`mboxMessage` instance is created based upon a
- :class:`BabylMessage` instance, the following conversions take place:
- +-------------------+-----------------------------+
- | Resulting state | :class:`BabylMessage` state |
- +===================+=============================+
- | R flag and O flag | no "unseen" label |
- +-------------------+-----------------------------+
- | O flag | "unseen" label |
- +-------------------+-----------------------------+
- | D flag | "deleted" label |
- +-------------------+-----------------------------+
- | A flag | "answered" label |
- +-------------------+-----------------------------+
- When a :class:`Message` instance is created based upon an :class:`MMDFMessage`
- instance, the "From " line is copied and all flags directly correspond:
- +-----------------+----------------------------+
- | Resulting state | :class:`MMDFMessage` state |
- +=================+============================+
- | R flag | R flag |
- +-----------------+----------------------------+
- | O flag | O flag |
- +-----------------+----------------------------+
- | D flag | D flag |
- +-----------------+----------------------------+
- | F flag | F flag |
- +-----------------+----------------------------+
- | A flag | A flag |
- +-----------------+----------------------------+
- .. _mailbox-mhmessage:
- :class:`MHMessage`
- ^^^^^^^^^^^^^^^^^^
- .. class:: MHMessage([message])
- A message with MH-specific behaviors. Parameter *message* has the same meaning
- as with the :class:`Message` constructor.
- MH messages do not support marks or flags in the traditional sense, but they
- do support sequences, which are logical groupings of arbitrary messages. Some
- mail reading programs (although not the standard :program:`mh` and
- :program:`nmh`) use sequences in much the same way flags are used with other
- formats, as follows:
- +----------+------------------------------------------+
- | Sequence | Explanation |
- +==========+==========================================+
- | unseen | Not read, but previously detected by MUA |
- +----------+------------------------------------------+
- | replied | Replied to |
- +----------+------------------------------------------+
- | flagged | Marked as important |
- +----------+------------------------------------------+
- :class:`MHMessage` instances offer the following methods:
- .. method:: get_sequences()
- Return a list of the names of sequences that include this message.
- .. method:: set_sequences(sequences)
- Set the list of sequences that include this message.
- .. method:: add_sequence(sequence)
- Add *sequence* to the list of sequences that include this message.
- .. method:: remove_sequence(sequence)
- Remove *sequence* from the list of sequences that include this message.
- When an :class:`MHMessage` instance is created based upon a
- :class:`MaildirMessage` instance, the following conversions take place:
- +--------------------+-------------------------------+
- | Resulting state | :class:`MaildirMessage` state |
- +====================+===============================+
- | "unseen" sequence | no S flag |
- +--------------------+-------------------------------+
- | "replied" sequence | R flag |
- +--------------------+-------------------------------+
- | "flagged" sequence | F flag |
- +--------------------+-------------------------------+
- When an :class:`MHMessage` instance is created based upon an
- :class:`mboxMessage` or :class:`MMDFMessage` instance, the :mailheader:`Status`
- and :mailheader:`X-Status` headers are omitted and the following conversions
- take place:
- +--------------------+----------------------------------------------+
- | Resulting state | :class:`mboxMessage` or :class:`MMDFMessage` |
- | | state |
- +====================+==============================================+
- | "unseen" sequence | no R flag |
- +--------------------+----------------------------------------------+
- | "replied" sequence | A flag |
- +--------------------+----------------------------------------------+
- | "flagged" sequence | F flag |
- +--------------------+----------------------------------------------+
- When an :class:`MHMessage` instance is created based upon a
- :class:`BabylMessage` instance, the following conversions take place:
- +--------------------+-----------------------------+
- | Resulting state | :class:`BabylMessage` state |
- +====================+=============================+
- | "unseen" sequence | "unseen" label |
- +--------------------+-----------------------------+
- | "replied" sequence | "answered" label |
- +--------------------+-----------------------------+
- .. _mailbox-babylmessage:
- :class:`BabylMessage`
- ^^^^^^^^^^^^^^^^^^^^^
- .. class:: BabylMessage([message])
- A message with Babyl-specific behaviors. Parameter *message* has the same
- meaning as with the :class:`Message` constructor.
- Certain message labels, called :dfn:`attributes`, are defined by convention
- to have special meanings. The attributes are as follows:
- +-----------+------------------------------------------+
- | Label | Explanation |
- +===========+==========================================+
- | unseen | Not read, but previously detected by MUA |
- +-----------+------------------------------------------+
- | deleted | Marked for subsequent deletion |
- +-----------+------------------------------------------+
- | filed | Copied to another file or mailbox |
- +-----------+------------------------------------------+
- | answered | Replied to |
- +-----------+------------------------------------------+
- | forwarded | Forwarded |
- +-----------+------------------------------------------+
- | edited | Modified by the user |
- +-----------+------------------------------------------+
- | resent | Resent |
- +-----------+------------------------------------------+
- By default, Rmail displays only visible headers. The :class:`BabylMessage`
- class, though, uses the original headers because they are more
- complete. Visible headers may be accessed explicitly if desired.
- :class:`BabylMessage` instances offer the following methods:
- .. method:: get_labels()
- Return a list of labels on the message.
- .. method:: set_labels(labels)
- Set the list of labels on the message to *labels*.
- .. method:: add_label(label)
- Add *label* to the list of labels on the message.
- .. method:: remove_label(label)
- Remove *label* from the list of labels on the message.
- .. method:: get_visible()
- Return an :class:`Message` instance whose headers are the message's
- visible headers and whose body is empty.
- .. method:: set_visible(visible)
- Set the message's visible headers to be the same as the headers in
- *message*. Parameter *visible* should be a :class:`Message` instance, an
- :class:`email.Message.Message` instance, a string, or a file-like object
- (which should be open in text mode).
- .. method:: update_visible()
- When a :class:`BabylMessage` instance's original headers are modified, the
- visible headers are not automatically modified to…