12.2.4 Creating email and MIME objects from scratch

Ordinarily, you get a message object structure by passing a file or some text to a parser, which parses the text and returns the root message object. However you can also build a complete message structure from scratch, or even individual Message objects by hand. In fact, you can also take an existing structure and add new Message objects, move them around, etc. This makes a very convenient interface for slicing-and-dicing MIME messages.

You can create a new object structure by creating Message instances, adding attachments and all the appropriate headers manually. For MIME messages though, the email package provides some convenient subclasses to make things easier. Each of these classes should be imported from a module with the same name as the class, from within the email package. E.g.:

from email.MIMEText import MIMEText

Here are the classes:

class MIMEBase( _maintype, _subtype, **_params)

This is the base class for all the MIME-specific subclasses of Message. Ordinarily you won't create instances specifically of MIMEBase, although you could. MIMEBase is provided primarily as a convenient base class for more specific MIME-aware subclasses.

_maintype is the Content-Type: major type (e.g. text or image), and _subtype is the Content-Type: minor type (e.g. plain or gif). _params is a parameter key/value dictionary and is passed directly to Message.add_header().

The MIMEBase class always adds a Content-Type: header (based on _maintype, _subtype, and _params), and a MIME-Version: header (always set to 1.0).

class MIMENonMultipart( ): A subclass of MIMEBase, this is an intermediate base class for MIME messages that are not multipart. The primary purpose of this class is to prevent the use of the attach() method, which only makes sense for multipart messages. If attach() is called, a MultipartConversionError exception is raised.
New in version 2.2.2.

class MIMEMultipart( [subtype[, boundary[, _subparts[, _params]]]])

A subclass of MIMEBase, this is an intermediate base class for MIME messages that are multipart. Optional _subtype defaults to mixed, but can be used to specify the subtype of the message. A Content-Type: header of multipart/_subtype will be added to the message object. A MIME-Version: header will also be added.

Optional boundary is the multipart boundary string. When None (the default), the boundary is calculated when needed.

_subparts is a sequence of initial subparts for the payload. It must be possible to convert this sequence to a list. You can always attach new subparts to the message by using the Message.attach() method.

Additional parameters for the Content-Type: header are taken from the keyword arguments, or passed into the _params argument, which is a keyword dictionary.

New in version 2.2.2.

class MIMEAudio( _audiodata[, _subtype[, _encoder[, **_params]]])

A subclass of MIMENonMultipart, the MIMEAudio class is used to create MIME message objects of major type audio. _audiodata is a string containing the raw audio data. If this data can be decoded by the standard Python module sndhdr, then the subtype will be automatically included in the Content-Type: header. Otherwise you can explicitly specify the audio subtype via the _subtype parameter. If the minor type could not be guessed and _subtype was not given, then TypeError is raised.

Optional _encoder is a callable (i.e. function) which will perform the actual encoding of the audio data for transport. This callable takes one argument, which is the MIMEAudio instance. It should use get_payload() and set_payload() to change the payload to encoded form. It should also add any Content-Transfer-Encoding: or other headers to the message object as necessary. The default encoding is base64. See the email.Encoders module for a list of the built-in encoders.

_params are passed straight through to the base class constructor.

class MIMEImage( _imagedata[, _subtype[, _encoder[, **_params]]])

A subclass of MIMENonMultipart, the MIMEImage class is used to create MIME message objects of major type image. _imagedata is a string containing the raw image data. If this data can be decoded by the standard Python module imghdr, then the subtype will be automatically included in the Content-Type: header. Otherwise you can explicitly specify the image subtype via the _subtype parameter. If the minor type could not be guessed and _subtype was not given, then TypeError is raised.

Optional _encoder is a callable (i.e. function) which will perform the actual encoding of the image data for transport. This callable takes one argument, which is the MIMEImage instance. It should use get_payload() and set_payload() to change the payload to encoded form. It should also add any Content-Transfer-Encoding: or other headers to the message object as necessary. The default encoding is base64. See the email.Encoders module for a list of the built-in encoders.

_params are passed straight through to the MIMEBase constructor.

class MIMEMessage( _msg[, _subtype]): A subclass of MIMENonMultipart, the MIMEMessage class is used to create MIME objects of main type message. _msg is used as the payload, and must be an instance of class Message (or a subclass thereof), otherwise a TypeError is raised.
Optional _subtype sets the subtype of the message; it defaults to rfc822.

class MIMEText( _text[, _subtype[, _charset]]): A subclass of MIMENonMultipart, the MIMEText class is used to create MIME objects of major type text. _text is the string for the payload. _subtype is the minor type and defaults to plain. _charset is the character set of the text and is passed as a parameter to the MIMENonMultipart constructor; it defaults to us-ascii. No guessing or encoding is performed on the text data.
Changed in version 2.4: The previously deprecated _encoding argument has been removed. Encoding happens implicitly based on the _charset argument.

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