18.1.12. 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.

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

• All modules have been renamed according to PEP 8 standards. For example, the version 3 module email.Message was renamed to email.message in version 4.

• A new subpackage email.mime was added and all the version 3 email.MIME* modules were renamed and situated into the email.mime subpackage. For example, the version 3 module email.MIMEText was renamed to email.mime.text.

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

• The email.mime.application module was added, which contains the MIMEApplication class.

• Methods that were deprecated in version 3 have been removed. These include Generator.__call__(), Message.get_type(), Message.get_main_type(), Message.get_subtype().

• Fixes have been added for RFC 2231 support which can change some of the return types for 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 email version 3 and version 2:

• The FeedParser class was introduced, and the Parser class was implemented in terms of the 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 DeprecationWarnings in version 2 have been removed. These include the _encoder argument to the MIMEText constructor, the Message.add_payload() method, the Utils.dump_address_pair() function, and the functions Utils.decode() and Utils.encode().
• New DeprecationWarnings have been added to: Generator.__call__(), Message.get_type(), Message.get_main_type(), Message.get_subtype(), and the strict argument to the 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 email version 2 and version 1:

• The email.Header and email.Charset modules have been added.

• The pickle format for 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 Message instances, be aware that in email version 2, Message instances now have private variables _charset and _default_type.

• Several methods in the Message class have been deprecated, or their signatures changed. Also, many new methods have been added. See the documentation for the Message class for details. The changes should be completely backward compatible.

• The object structure has changed in the face of message/rfc822 content types. In email version 1, such a type would be represented by a scalar payload, i.e. the container message’s is_multipart() returned false, get_payload() was not a list object, but a single Message instance.

  This structure was inconsistent with the rest of the package, so the object representation for message/rfc822 content types was changed. In email version 2, the container does return True from is_multipart(), and get_payload() returns a list containing a single 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 get_payload(), you should be fine. You just need to make sure your code doesn’t do a set_payload() with a Message instance on a container with a content type of message/rfc822.

• The Parser constructor’s strict argument was added, and its parse() and parsestr() methods grew a headersonly argument. The strict flag was also added to functions email.message_from_file() and email.message_from_string().

• Generator.__call__() is deprecated; use Generator.flatten() instead. The Generator class has also grown the clone() method.

• The DecodedGenerator class in the email.Generator module was added.

• The intermediate base classes MIMENonMultipart and MIMEMultipart have been added, and interposed in the class hierarchy for most of the other MIME-related derived classes.

• The _encoder argument to the MIMEText constructor has been deprecated. Encoding now happens implicitly based on the _charset argument.

• The following functions in the email.Utils module have been deprecated: dump_address_pairs(), decode(), and encode(). The following functions have been added to the module: make_msgid(), decode_rfc2231(), encode_rfc2231(), and decode_params().

• The non-public function email.Iterators._structure() was added.

18.1.13. Differences from mimelib

The email package was originally prototyped as a separate library called mimelib. 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 mimelib is still available in the email package, albeit often in a different way. Backward compatibility between the mimelib package and the email package was not a priority.

Here is a brief description of the differences between the mimelib and the 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 email. In addition, the top-level package has the following differences:

• messageFromString() has been renamed to message_from_string().
• messageFromFile() has been renamed to message_from_file().

The Message class has the following differences:

• The method asString() was renamed to as_string().
• The method ismultipart() was renamed to is_multipart().
• The get_payload() method has grown a decode optional argument.
• The method getall() was renamed to get_all().
• The method addheader() was renamed to add_header().
• The method gettype() was renamed to get_type().
• The method getmaintype() was renamed to get_main_type().
• The method getsubtype() was renamed to get_subtype().
• The method getparams() was renamed to get_params(). Also, whereas getparams() returned a list of strings, get_params() returns a list of 2-tuples, effectively the key/value pairs of the parameters, split on the '=' sign.
• The method getparam() was renamed to get_param().
• The method getcharsets() was renamed to get_charsets().
• The method getfilename() was renamed to get_filename().
• The method getboundary() was renamed to get_boundary().
• The method setboundary() was renamed to set_boundary().
• The method getdecodedpayload() was removed. To get similar functionality, pass the value 1 to the decode flag of the get_payload() method.
• The method getpayloadastext() was removed. Similar functionality is supported by the DecodedGenerator class in the email.generator module.
• The method getbodyastext() was removed. You can get similar functionality by creating an iterator with typed_subpart_iterator() in the email.iterators module.

The Parser class has no differences in its public interface. It does have some additional smarts to recognize message/delivery-status type messages, which it represents as a Message instance containing separate Message subparts for each header block in the delivery status notification [1].

The Generator class has no differences in its public interface. There is a new class in the email.generator module though, called DecodedGenerator which provides most of the functionality previously available in the Message.getpayloadastext() method.

The following modules and classes have been changed:

• The 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 mimelib called this class/module RFC822, but that clashed with the Python standard library module rfc822 on some case-insensitive file systems.

  Also, the MIMEMessage class now represents any kind of MIME message with main type message. It takes an optional argument _subtype which is used to set the MIME subtype. _subtype defaults to rfc822.

mimelib provided some utility functions in its address and date modules. All of these functions have been moved to the email.utils module.

The MsgReader class/module has been removed. Its functionality is most closely supported in the body_line_iterator() function in the email.iterators module.

Footnotes