The central class in the email package is the
Message class, imported from the email.message module. 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.
Here are the methods of the Message class:
-
The constructor takes no arguments.
-
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 .
Note that this method is provided as a convenience and may not always format
the message the way you want. For example, by default it mangles lines that
begin with From . For more flexibility, instantiate a
Generator instance and use its
flatten() method directly. For example:
from cStringIO import StringIO
from email.generator import Generator
fp = StringIO()
g = Generator(fp, mangle_from_=False, maxheaderlen=60)
g.flatten(msg)
text = fp.getvalue()
-
Equivalent to as_string(unixfrom=True).
-
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.
-
Set the message's envelope header to unixfrom, which should be a string.
-
Return the message's envelope header. Defaults to
None if the
envelope header was never set.
-
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.
get_payload( |
[i[, decode]]) |
-
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 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
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_payload( |
payload[, charset]) |
-
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.
Changed in version 2.2.2:
charset argument added.
-
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
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
(, ,
) will be added as needed.
New in version 2.2.2.
-
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 the total number of headers, including duplicates.
-
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!'
-
Delete all occurrences of the field with name name from the
message's headers. No exception is raised if the named field isn't
present in the headers.
-
Return true if the message contains a header field named name,
otherwise return false.
-
Return a list of all the message's header field names.
-
Return a list of all the message's field values.
-
Return a list of 2-tuples containing all the message's field headers
and values.
-
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 ).
Here are some additional useful methods:
get_all( |
name[, failobj]) |
-
Return a list of all the values for the field named name.
If there are no such named headers in the message, failobj is
returned (defaults to
None ).
add_header( |
_name, _value, **_params) |
-
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.
Here's an example:
msg.add_header('Content-Disposition', 'attachment', filename='bud.gif')
This will add a header that looks like
Content-Disposition: attachment; filename="bud.gif"
replace_header( |
_name, _value) |
-
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.
New in version 2.2.2.
-
Return the message's content type. The returned string is coerced to
lower case of the form maintype/subtype. If there was no
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 header
has an invalid type specification, RFC 2045 mandates that the
default type be text/plain.
New in version 2.2.2.
-
Return the message's main content type. This is the
maintype part of the string returned by
get_content_type().
New in version 2.2.2.
-
Return the message's sub-content type. This is the subtype
part of the string returned by get_content_type().
New in version 2.2.2.
-
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.
New in version 2.2.2.
-
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
header.
New in version 2.2.2.
get_params( |
[failobj[,
header[, unquote]]]) |
-
Return the message's 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
header. Optional header is the header to
search instead of .
Changed in version 2.2.2:
unquote argument added.
get_param( |
param[,
failobj[, header[, unquote]]]) |
-
Return the value of the header's parameter
param as a string. If the message has no
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 .
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) . Note that both CHARSET and
LANGUAGE can be None , in which case you should consider
VALUE to be encoded in the us-ascii charset. You can
usually ignore LANGUAGE .
If your application doesn't care whether the parameter was encoded as in
RFC 2231, you can collapse the parameter value by calling
email.Utils.collapse_rfc2231_value(), passing in the return value
from get_param(). This will return a suitably decoded Unicode string
whn the value is a tuple, or the original string unquoted if it isn't. For
example:
rawparam = msg.get_param('foo')
param = email.Utils.collapse_rfc2231_value(rawparam)
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_param( |
param, value[,
header[, requote[, charset[, language]]]]) |
-
Set a parameter in the header. If the
parameter already exists in the header, its value will be replaced
with value. If the 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
, 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.
New in version 2.2.2.
del_param( |
param[, header[,
requote]]) |
-
Remove the given parameter completely from the
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
.
New in version 2.2.2.
set_type( |
type[, header][,
requote]) |
-
Set the main type and subtype for the
header. type must be a string in the form
maintype/subtype, otherwise a ValueError is
raised.
This method replaces the 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 header is set a
header is also added.
New in version 2.2.2.
-
Return the value of the
filename parameter of the
header of the message. If the header does
not have a filename parameter, this method falls back to looking for
the name parameter. If neither is found, or the header is missing,
then failobj is returned. The returned string will always be unquoted
as per Utils.unquote().
-
Return the value of the
boundary parameter of the
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
header to boundary. set_boundary() will always quote
boundary if necessary. A HeaderParseError is raised
if the message object has no header.
Note that using this method is subtly different than deleting the old
header and adding a new one with the new boundary
via add_header(), because set_boundary() preserves the
order of the header in the list of headers.
However, it does not preserve any continuation lines which may
have been present in the original header.
get_content_charset( |
[failobj]) |
-
Return the
charset parameter of the
header, coerced to lower case. If there is no
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.
New in version 2.2.2.
-
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 header for the
represented subpart. However, if the subpart has no
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
Changed in version 2.5:
The previously deprecated methods get_type(),
get_main_type(), and get_subtype() were removed.
Message objects can also optionally contain two instance
attributes, which can be used when generating the plain text of a MIME
message.
- preamble
-
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 .
- epilogue
-
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.
Changed in version 2.5:
You do not need to set the epilogue to the empty string in
order for the Generator to print a newline at the end of the
file.
- defects
-
The defects attribute contains a list of all the problems found when
parsing this message. See email.errors for a detailed description
of the possible parsing defects.
New in version 2.4.
Release 2.5.2, documentation updated on 21st February, 2008.
See About this document... for information on suggesting changes.
|