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.. module:: email.encoders
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:synopsis: Encoders for email message payloads.
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When creating :class:`Message` objects from scratch, you often need to encode
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the payloads for transport through compliant mail servers. This is especially
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true for :mimetype:`image/\*` and :mimetype:`text/\*` type messages containing
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The :mod:`email` package provides some convenient encodings in its
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:mod:`encoders` module. These encoders are actually used by the
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:class:`MIMEAudio` and :class:`MIMEImage` class constructors to provide default
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encodings. All encoder functions take exactly one argument, the message object
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to encode. They usually extract the payload, encode it, and reset the payload
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to this newly encoded value. They should also set the
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:mailheader:`Content-Transfer-Encoding` header as appropriate.
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Here are the encoding functions provided:
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.. function:: encode_quopri(msg)
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Encodes the payload into quoted-printable form and sets the
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:mailheader:`Content-Transfer-Encoding` header to ``quoted-printable`` [#]_.
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This is a good encoding to use when most of your payload is normal printable
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data, but contains a few unprintable characters.
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.. function:: encode_base64(msg)
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Encodes the payload into base64 form and sets the
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:mailheader:`Content-Transfer-Encoding` header to ``base64``. This is a good
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encoding to use when most of your payload is unprintable data since it is a more
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compact form than quoted-printable. The drawback of base64 encoding is that it
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renders the text non-human readable.
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.. function:: encode_7or8bit(msg)
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This doesn't actually modify the message's payload, but it does set the
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:mailheader:`Content-Transfer-Encoding` header to either ``7bit`` or ``8bit`` as
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appropriate, based on the payload data.
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.. function:: encode_noop(msg)
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This does nothing; it doesn't even set the
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:mailheader:`Content-Transfer-Encoding` header.
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.. [#] Note that encoding with :meth:`encode_quopri` also encodes all tabs and space
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characters in the data.