The central class in the email package is the
Message class; it is the base class for the email
object model. Message provides the core functionality for
setting and querying header fields, and for accessing message bodies.
Conceptually, a Message object consists of headers and
payloads. Headers are RFC 2822 style field names and
values where the field name and value are separated by a colon. The
colon is not part of either the field name or the field value.
Headers are stored and returned in case-preserving form but are
matched case-insensitively. There may also be a single envelope
header, also known as the Unix-From header or the
From_ header. The payload is either a string in the case of
simple message objects or a list of Message objects for
MIME container documents (e.g. multipart/* and
message/rfc822).
Message objects provide a mapping style interface for
accessing the message headers, and an explicit interface for accessing
both the headers and the payload. It provides convenience methods for
generating a flat text representation of the message object tree, for
accessing commonly used header parameters, and for recursively walking
over the object tree.
Return the entire message flatten as a string. When optional
unixfrom is True, the envelope header is included in the
returned string. unixfrom defaults to False.
Return True if the message's payload is a list of
sub-Message objects, otherwise return False. When
is_multipart() returns False, the payload should be a string
object.
Add the given payload to the current payload, which must be
None or a list of Message objects before the call.
After the call, the payload will always be a list of Message
objects. If you want to set the payload to a scalar object (e.g. a
string), use set_payload() instead.
Return a reference the current payload, which will be a list of
Message objects when is_multipart() is True, or a
string when is_multipart() is False. If the
payload is a list and you mutate the list object, you modify the
message's payload in place.
With optional argument i, get_payload() will return the
i-th element of the payload, counting from zero, if
is_multipart() is True. An IndexError
will be raised if i is less than 0 or greater than or equal to
the number of items in the payload. If the payload is a string
(i.e. is_multipart() is False) and i is given, a
TypeError is raised.
Optional decode is a flag indicating whether the payload should be
decoded or not, according to the Content-Transfer-Encoding: header.
When True and the message is not a multipart, the payload will be
decoded if this header's value is "quoted-printable" or
"base64". If some other encoding is used, or
Content-Transfer-Encoding: header is
missing, or if the payload has bogus base64 data, the payload is
returned as-is (undecoded). If the message is a multipart and the
decode flag is True, then None is returned. The
default for decode is False.
Set the entire message object's payload to payload. It is the
client's responsibility to ensure the payload invariants. Optional
charset sets the message's default character set; see
set_charset() for details.
Set the character set of the payload to charset, which can
either be a Charset instance (see email.Charset), a
string naming a character set,
or None. If it is a string, it will be converted to a
Charset instance. If charset is None, the
charset parameter will be removed from the
Content-Type: header. Anything else will generate a
TypeError.
The message will be assumed to be of type text/* encoded with
charset.input_charset. It will be converted to
charset.output_charset
and encoded properly, if needed, when generating the plain text
representation of the message. MIME headers
(MIME-Version:, Content-Type:,
Content-Transfer-Encoding:) will be added as needed.
Return the Charset instance associated with the message's payload.
New in version 2.2.2.
The following methods implement a mapping-like interface for accessing
the message's RFC 2822 headers. Note that there are some
semantic differences between these methods and a normal mapping
(i.e. dictionary) interface. For example, in a dictionary there are
no duplicate keys, but here there may be duplicate message headers. Also,
in dictionaries there is no guaranteed order to the keys returned by
keys(), but in a Message object, headers are always
returned in the order they appeared in the original message, or were
added to the message later. Any header deleted and then re-added are
always appended to the end of the header list.
These semantic differences are intentional and are biased toward
maximal convenience.
Note that in all cases, any envelope header present in the message is
not included in the mapping interface.
Return true if the message object has a field named name.
Matching is done case-insensitively and name should not include the
trailing colon. Used for the in operator,
e.g.:
if 'message-id' in myMessage:
print 'Message-ID:', myMessage['message-id']
Return the value of the named header field. name should not
include the colon field separator. If the header is missing,
None is returned; a KeyError is never raised.
Note that if the named field appears more than once in the message's
headers, exactly which of those field values will be returned is
undefined. Use the get_all() method to get the values of all
the extant named headers.
Add a header to the message with field name name and value
val. The field is appended to the end of the message's existing
fields.
Note that this does not overwrite or delete any existing header
with the same name. If you want to ensure that the new header is the
only one present in the message with field name
name, delete the field first, e.g.:
del msg['subject']
msg['subject'] = 'Python roolz!'
Return the value of the named header field. This is identical to
__getitem__() except that optional failobj is returned
if the named header is missing (defaults to None).
Extended header setting. This method is similar to
__setitem__() except that additional header parameters can be
provided as keyword arguments. _name is the header field to add
and _value is the primary value for the header.
For each item in the keyword argument dictionary _params, the
key is taken as the parameter name, with underscores converted to
dashes (since dashes are illegal in Python identifiers). Normally,
the parameter will be added as key="value" unless the value is
None, in which case only the key will be added.
Replace a header. Replace the first header found in the message that
matches _name, retaining header order and field name case. If
no matching header was found, a KeyError is raised.
Return the message's content type. The returned string is coerced to
lower case of the form maintype/subtype. If there was no
Content-Type: header in the message the default type as
given by get_default_type() will be returned. Since
according to RFC 2045, messages always have a default type,
get_content_type() will always return a value.
RFC 2045 defines a message's default type to be
text/plain unless it appears inside a
multipart/digest container, in which case it would be
message/rfc822. If the Content-Type: header
has an invalid type specification, RFC 2045 mandates that the
default type be text/plain.
Return the default content type. Most messages have a default content
type of text/plain, except for messages that are subparts
of multipart/digest containers. Such subparts have a
default content type of message/rfc822.
Set the default content type. ctype should either be
text/plain or message/rfc822, although this is
not enforced. The default content type is not stored in the
Content-Type: header.
Return the message's Content-Type: parameters, as a list. The
elements of the returned list are 2-tuples of key/value pairs, as
split on the "=" sign. The left hand side of the
"=" is the key, while the right hand side is the value. If
there is no "=" sign in the parameter the value is the empty
string, otherwise the value is as described in get_param() and is
unquoted if optional unquote is True (the default).
Optional failobj is the object to return if there is no
Content-Type: header. Optional header is the header to
search instead of Content-Type:.
Return the value of the Content-Type: header's parameter
param as a string. If the message has no Content-Type:
header or if there is no such parameter, then failobj is
returned (defaults to None).
Optional header if given, specifies the message header to use
instead of Content-Type:.
Parameter keys are always compared case insensitively. The return
value can either be a string, or a 3-tuple if the parameter was
RFC 2231 encoded. When it's a 3-tuple, the elements of the value are of
the form (CHARSET, LANGUAGE, VALUE), where LANGUAGE may
be the empty string. Your application should be prepared to deal with
3-tuple return values, which it can convert to a Unicode string like
so:
param = msg.get_param('foo')
if isinstance(param, tuple):
param = unicode(param[2], param[0])
In any case, the parameter value (either the returned string, or the
VALUE item in the 3-tuple) is always unquoted, unless
unquote is set to False.
Changed in version 2.2.2:
unquote argument added, and 3-tuple return value
possible.
Set a parameter in the Content-Type: header. If the
parameter already exists in the header, its value will be replaced
with value. If the Content-Type: header as not yet
been defined for this message, it will be set to text/plain
and the new parameter value will be appended as per RFC 2045.
Optional header specifies an alternative header to
Content-Type:, and all parameters will be quoted as
necessary unless optional requote is False (the default
is True).
If optional charset is specified, the parameter will be encoded
according to RFC 2231. Optional language specifies the RFC
2231 language, defaulting to the empty string. Both charset and
language should be strings.
Remove the given parameter completely from the
Content-Type: header. The header will be re-written in
place without the parameter or its value. All values will be quoted
as necessary unless requote is False (the default is
True). Optional header specifies an alternative to
Content-Type:.
Set the main type and subtype for the Content-Type:
header. type must be a string in the form
maintype/subtype, otherwise a ValueError is
raised.
This method replaces the Content-Type: header, keeping all
the parameters in place. If requote is False, this
leaves the existing header's quoting as is, otherwise the parameters
will be quoted (the default).
An alternative header can be specified in the header argument.
When the Content-Type: header is set a
MIME-Version: header is also added.
Return the value of the filename parameter of the
Content-Disposition: header of the message, or failobj if
either the header is missing, or has no filename parameter.
The returned string will always be unquoted as per
Utils.unquote().
Return the value of the boundary parameter of the
Content-Type: header of the message, or failobj if either
the header is missing, or has no boundary parameter. The
returned string will always be unquoted as per
Utils.unquote().
Set the boundary parameter of the Content-Type:
header to boundary. set_boundary() will always quote
boundary if necessary. A HeaderParseError is raised
if the message object has no Content-Type: header.
Note that using this method is subtly different than deleting the old
Content-Type: header and adding a new one with the new boundary
via add_header(), because set_boundary() preserves the
order of the Content-Type: header in the list of headers.
However, it does not preserve any continuation lines which may
have been present in the original Content-Type: header.
Return the charset parameter of the Content-Type:
header, coerced to lower case. If there is no
Content-Type: header, or if that header has no
charset parameter, failobj is returned.
Note that this method differs from get_charset() which
returns the Charset instance for the default encoding of the
message body.
Return a list containing the character set names in the message. If
the message is a multipart, then the list will contain one
element for each subpart in the payload, otherwise, it will be a list
of length 1.
Each item in the list will be a string which is the value of the
charset parameter in the Content-Type: header for the
represented subpart. However, if the subpart has no
Content-Type: header, no charset parameter, or is not of
the text main MIME type, then that item in the returned list
will be failobj.
The walk() method is an all-purpose generator which can be
used to iterate over all the parts and subparts of a message object
tree, in depth-first traversal order. You will typically use
walk() as the iterator in a for loop; each
iteration returns the next subpart.
Here's an example that prints the MIME type of every part of a
multipart message structure:
>>> for part in msg.walk():
>>> print part.get_content_type()
multipart/report
text/plain
message/delivery-status
text/plain
text/plain
message/rfc822
Message objects can also optionally contain two instance
attributes, which can be used when generating the plain text of a MIME
message.
The format of a MIME document allows for some text between the blank
line following the headers, and the first multipart boundary string.
Normally, this text is never visible in a MIME-aware mail reader
because it falls outside the standard MIME armor. However, when
viewing the raw text of the message, or when viewing the message in a
non-MIME aware reader, this text can become visible.
The preamble attribute contains this leading extra-armor text
for MIME documents. When the Parser discovers some text after
the headers but before the first boundary string, it assigns this text
to the message's preamble attribute. When the Generator
is writing out the plain text representation of a MIME message, and it
finds the message has a preamble attribute, it will write this
text in the area between the headers and the first boundary. See
email.Parser and email.Generator for details.
Note that if the message object has no preamble, the
preamble attribute will be None.
The epilogue attribute acts the same way as the preamble
attribute, except that it contains text that appears between the last
boundary and the end of the message.
One note: when generating the flat text for a multipart
message that has no epilogue (using the standard
Generator class), no newline is added after the closing
boundary line. If the message object has an epilogue and its
value does not start with a newline, a newline is printed after the
closing boundary. This seems a little clumsy, but it makes the most
practical sense. The upshot is that if you want to ensure that a
newline get printed after your closing multipart boundary,
set the epilogue to the empty string.
