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. If the value contains non-ASCII characters, the charset and language may be explicitly controlled by specifying the value as a three tuple in the format (CHARSET, LANGUAGE, VALUE), where CHARSET is a string naming the charset to be used to encode the value, LANGUAGE can usually be set to None or the empty string (see RFC 2231 for other possibilities), and VALUE is the string value containing non-ASCII code points. If a three tuple is not passed and the value contains non-ASCII characters, it is automatically encoded in RFC 2231 format using a CHARSET of utf-8 and a LANGUAGE of None. Here is 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"
 An example of the extended interface with non-ASCII characters: msg.add_header('Content-Disposition', 'attachment',
               filename=('iso-8859-1', '', 'Fußballer.ppt'))


add_related(*args, content_manager=None, **kw)
If the message is a multipart/related, create a new message object, pass all of the arguments to its set_content() method, and attach() it to the multipart. If the message is a non-multipart, call make_related() and then proceed as above. If the message is any other type of multipart, raise a TypeError. If content_manager is not specified, use the content_manager specified by the current policy. If the added part has no Content-Disposition header, add one with the value inline.


as_bytes(unixfrom=False, policy=None)
Return the entire message flattened as a bytes object. When optional unixfrom is true, the envelope header is included in the returned string. unixfrom defaults to False. The policy argument may be used to override the default policy obtained from the message instance. This can be used to control some of the formatting produced by the method, since the specified policy will be passed to the BytesGenerator. Flattening the message may trigger changes to the EmailMessage if defaults need to be filled in to complete the transformation to a string (for example, MIME boundaries may be generated or modified). Note that this method is provided as a convenience and may not be the most useful way to serialize messages in your application, especially if you are dealing with multiple messages. See email.generator.BytesGenerator for a more flexible API for serializing messages.


as_string(unixfrom=False, maxheaderlen=None, policy=None)
Return the entire message flattened as a string. When optional unixfrom is true, the envelope header is included in the returned string. unixfrom defaults to False. For backward compatibility with the base Message class maxheaderlen is accepted, but defaults to None, which means that by default the line length is controlled by the max_line_length of the policy. The policy argument may be used to override the default policy obtained from the message instance. This can be used to control some of the formatting produced by the method, since the specified policy will be passed to the Generator. Flattening the message may trigger changes to the EmailMessage if defaults need to be filled in to complete the transformation to a string (for example, MIME boundaries may be generated or modified). Note that this method is provided as a convenience and may not be the most useful way to serialize messages in your application, especially if you are dealing with multiple messages. See email.generator.Generator for a more flexible API for serializing messages. Note also that this method is restricted to producing messages serialized as “7 bit clean” when utf8 is False, which is the default.  Changed in version 3.6: the default behavior when maxheaderlen is not specified was changed from defaulting to 0 to defaulting to the value of max_line_length from the policy.


clear()
Remove the payload and all of the headers.


clear_content()
Remove the payload and all of the Content- headers, leaving all other headers intact and in their original order.


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.


del_param(param, header='content-type', requote=True)
Remove the given parameter completely from the Content-Type header. The header will be re-written in place without the parameter or its value. Optional header specifies an alternative to Content-Type. Use of the requote parameter with EmailMessage objects is deprecated.


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. As with the preamble, if there is no epilog text this attribute will be None.


get(name, failobj=None)
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 (failobj defaults to None).


get_all(name, failobj=None)
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).


get_body(preferencelist=('related', 'html', 'plain'))
Return the MIME part that is the best candidate to be the “body” of the message. preferencelist must be a sequence of strings from the set related, html, and plain, and indicates the order of preference for the content type of the part returned. Start looking for candidate matches with the object on which the get_body method is called. If related is not included in preferencelist, consider the root part (or subpart of the root part) of any related encountered as a candidate if the (sub-)part matches a preference. When encountering a multipart/related, check the start parameter and if a part with a matching Content-ID is found, consider only it when looking for candidate matches. Otherwise consider only the first (default root) part of the multipart/related. If a part has a Content-Disposition header, only consider the part a candidate match if the value of the header is inline. If none of the candidates matches any of the preferences in preferencelist, return None. Notes: (1) For most applications the only preferencelist combinations that really make sense are ('plain',), ('html', 'plain'), and the default ('related', 'html', 'plain'). (2) Because matching starts with the object on which get_body is called, calling get_body on a multipart/related will return the object itself unless preferencelist has a non-default value. (3) Messages (or message parts) that do not specify a Content-Type or whose Content-Type header is invalid will be treated as if they are of type text/plain, which may occasionally cause get_body to return unexpected results.


get_boundary(failobj=None)
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 email.utils.unquote().


get_charsets(failobj=None)
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. 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.


get_content(*args, content_manager=None, **kw)
Call the get_content() method of the content_manager, passing self as the message object, and passing along any other arguments or keywords as additional arguments. If content_manager is not specified, use the content_manager specified by the current policy.


get_content_charset(failobj=None)
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.


get_content_disposition()
Return the lowercased value (without parameters) of the message’s Content-Disposition header if it has one, or None. The possible values for this method are inline, attachment or None if the message follows RFC 2183.  New in version 3.5.


get_content_maintype()
Return the message’s main content type. This is the maintype part of the string returned by get_content_type().


get_content_subtype()
Return the message’s sub-content type. This is the subtype part of the string returned by get_content_type().


get_content_type()
Return the message’s content type, coerced to lower case of the form maintype/subtype. If there is no Content-Type header in the message return the value returned by get_default_type(). If the Content-Type header is invalid, return text/plain. (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.)


get_default_type()
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.


get_filename(failobj=None)
Return the value of the filename parameter of the Content-Disposition header of the message. If the header does not have a filename parameter, this method falls back to looking for the name parameter on the Content-Type header. If neither is found, or the header is missing, then failobj is returned. The returned string will always be unquoted as per email.utils.unquote().


get_unixfrom()
Return the message’s envelope header. Defaults to None if the envelope header was never set.


is_attachment()
Return True if there is a Content-Disposition header and its (case insensitive) value is attachment, False otherwise.  Changed in version 3.4.2: is_attachment is now a method instead of a property, for consistency with is_multipart().


is_multipart()
Return True if the message’s payload is a list of sub-EmailMessage objects, otherwise return False. When is_multipart() returns False, the payload should be a string object (which might be a CTE encoded binary payload). Note that is_multipart() returning True does not necessarily mean that “msg.get_content_maintype() == ‘multipart’” will return the True. For example, is_multipart will return True when the EmailMessage is of type message/rfc822.


items()
Return a list of 2-tuples containing all the message’s field headers and values.


iter_attachments()
Return an iterator over all of the immediate sub-parts of the message that are not candidate “body” parts. That is, skip the first occurrence of each of text/plain, text/html, multipart/related, or multipart/alternative (unless they are explicitly marked as attachments via Content-Disposition: attachment), and return all remaining parts. When applied directly to a multipart/related, return an iterator over the all the related parts except the root part (ie: the part pointed to by the start parameter, or the first part if there is no start parameter or the start parameter doesn’t match the Content-ID of any of the parts). When applied directly to a multipart/alternative or a non-multipart, return an empty iterator.


iter_parts()
Return an iterator over all of the immediate sub-parts of the message, which will be empty for a non-multipart. (See also walk().)


keys()
Return a list of all the message’s header field names.


make_alternative(boundary=None)
Convert a non-multipart or a multipart/related into a multipart/alternative, moving any existing Content- headers and payload into a (new) first part of the multipart. If boundary is specified, use it as the boundary string in the multipart, otherwise leave the boundary to be automatically created when it is needed (for example, when the message is serialized).


make_mixed(boundary=None)
Convert a non-multipart, a multipart/related, or a multipart-alternative into a multipart/mixed, moving any existing Content- headers and payload into a (new) first part of the multipart. If boundary is specified, use it as the boundary string in the multipart, otherwise leave the boundary to be automatically created when it is needed (for example, when the message is serialized).


make_related(boundary=None)
Convert a non-multipart message into a multipart/related message, moving any existing Content- headers and payload into a (new) first part of the multipart. If boundary is specified, use it as the boundary string in the multipart, otherwise leave the boundary to be automatically created when it is needed (for example, when the message is serialized).


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.


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 of the original header. If no matching header is found, raise a KeyError.


set_boundary(boundary)
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 from 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.


set_content(*args, content_manager=None, **kw)
Call the set_content() method of the content_manager, passing self as the message object, and passing along any other arguments or keywords as additional arguments. If content_manager is not specified, use the content_manager specified by the current policy.


set_default_type(ctype)
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, so it only affects the return value of the get_content_type methods when no Content-Type header is present in the message.


set_param(param, value, header='Content-Type', requote=True, charset=None, language='', replace=False)
Set a parameter in the Content-Type header. If the parameter already exists in the header, replace its value with value. When header is Content-Type (the default) and the header does not yet exist in the message, add it, set its value to text/plain, and append the new parameter value. Optional header specifies an alternative header to Content-Type. If the value contains non-ASCII characters, the charset and language may be explicitly specified using the optional charset and language parameters. Optional language specifies the RFC 2231 language, defaulting to the empty string. Both charset and language should be strings. The default is to use the utf8 charset and None for the language. If replace is False (the default) the header is moved to the end of the list of headers. If replace is True, the header will be updated in place. Use of the requote parameter with EmailMessage objects is deprecated. Note that existing parameter values of headers may be accessed through the params attribute of the header value (for example, msg['Content-Type'].params['charset']).  Changed in version 3.4: replace keyword was added.


set_unixfrom(unixfrom)
Set the message’s envelope header to unixfrom, which should be a string. (See mboxMessage for a brief description of this header.)


values()
Return a list of all the message’s field values.


walk()
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
text/plain
 walk iterates over the subparts of any part where is_multipart() returns True, even though msg.get_content_maintype() == 'multipart' may return False. We can see this in our example by making use of the _structure debug helper function: >>> from email.iterators import _structure
>>> for part in msg.walk():
...     print(part.get_content_maintype() == 'multipart',
...           part.is_multipart())
True True
False False
False True
False False
False False
False True
False False
>>> _structure(msg)
multipart/report
    text/plain
    message/delivery-status
        text/plain
        text/plain
    message/rfc822
        text/plain
 Here the message parts are not multiparts, but they do contain subparts. is_multipart() returns True and walk descends into the subparts.


__bytes__()
Equivalent to as_bytes(). Allows bytes(msg) to produce a bytes object containing the serialized message.


__contains__(name)
Return True if the message object has a field named name. Matching is done without regard to case and name does not include the trailing colon. Used for the in operator. For example: if 'message-id' in myMessage:
   print('Message-ID:', myMessage['message-id'])


__delitem__(name)
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.


__getitem__(name)
Return the value of the named header field. name does 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 headers named name. Using the standard (non-compat32) policies, the returned value is an instance of a subclass of email.headerregistry.BaseHeader.


__len__()
Return the total number of headers, including duplicates.


__setitem__(name, val)
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 headers. 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!'
 If the policy defines certain headers to be unique (as the standard policies do), this method may raise a ValueError when an attempt is made to assign a value to such a header when one already exists. This behavior is intentional for consistency’s sake, but do not depend on it as we may choose to make such assignments do an automatic deletion of the existing header in the future.


__str__()
Equivalent to as_string(policy=self.policy.clone(utf8=True)). Allows str(msg) to produce a string containing the serialized message in a readable format.  Changed in version 3.4: the method was changed to use utf8=True, thus producing an RFC 6531-like message representation, instead of being a direct alias for as_string().


class email.message.Message(policy=compat32)
If policy is specified (it must be an instance of a policy class) use the rules it specifies to update and serialize the representation of the message. If policy is not set, use the compat32 policy, which maintains backward compatibility with the Python 3.2 version of the email package. For more information see the policy documentation.  Changed in version 3.3: The policy keyword argument was added.
as_string(unixfrom=False, maxheaderlen=0, policy=None)
Return the entire message flattened as a string. When optional unixfrom is true, the envelope header is included in the returned string. unixfrom defaults to False. For backward compatibility reasons, maxheaderlen defaults to 0, so if you want a different value you must override it explicitly (the value specified for max_line_length in the policy will be ignored by this method). The policy argument may be used to override the default policy obtained from the message instance. This can be used to control some of the formatting produced by the method, since the specified policy will be passed to the Generator. Flattening the message may trigger changes to the Message if defaults need to be filled in to complete the transformation to a string (for example, MIME boundaries may be generated or modified). 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 does not do the mangling of lines that begin with From that is required by the unix mbox format. For more flexibility, instantiate a Generator instance and use its flatten() method directly. For example: from io import StringIO
from email.generator import Generator
fp = StringIO()
g = Generator(fp, mangle_from_=True, maxheaderlen=60)
g.flatten(msg)
text = fp.getvalue()
 If the message object contains binary data that is not encoded according to RFC standards, the non-compliant data will be replaced by unicode “unknown character” code points. (See also as_bytes() and BytesGenerator.)  Changed in version 3.4: the policy keyword argument was added.

__str__()
Equivalent to as_string(). Allows str(msg) to produce a string containing the formatted message.

as_bytes(unixfrom=False, policy=None)
Return the entire message flattened as a bytes object. When optional unixfrom is true, the envelope header is included in the returned string. unixfrom defaults to False. The policy argument may be used to override the default policy obtained from the message instance. This can be used to control some of the formatting produced by the method, since the specified policy will be passed to the BytesGenerator. Flattening the message may trigger changes to the Message if defaults need to be filled in to complete the transformation to a string (for example, MIME boundaries may be generated or modified). 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 does not do the mangling of lines that begin with From that is required by the unix mbox format. For more flexibility, instantiate a BytesGenerator instance and use its flatten() method directly. For example: from io import BytesIO
from email.generator import BytesGenerator
fp = BytesIO()
g = BytesGenerator(fp, mangle_from_=True, maxheaderlen=60)
g.flatten(msg)
text = fp.getvalue()
  New in version 3.4.

__bytes__()
Equivalent to as_bytes(). Allows bytes(msg) to produce a bytes object containing the formatted message.  New in version 3.4.

is_multipart()
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 (which might be a CTE encoded binary payload). (Note that is_multipart() returning True does not necessarily mean that “msg.get_content_maintype() == ‘multipart’” will return the True. For example, is_multipart will return True when the Message is of type message/rfc822.)

set_unixfrom(unixfrom)
Set the message’s envelope header to unixfrom, which should be a string.

get_unixfrom()
Return the message’s envelope header. Defaults to None if the envelope header was never set.

attach(payload)
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. This is a legacy method. On the EmailMessage class its functionality is replaced by set_content() and the related make and add methods.

get_payload(i=None, decode=False)
Return 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, the payload is returned as-is (undecoded). In all cases the returned value is binary data. If the message is a multipart and the decode flag is True, then None is returned. If the payload is base64 and it was not perfectly formed (missing padding, characters outside the base64 alphabet), then an appropriate defect will be added to the message’s defect property (InvalidBase64PaddingDefect or InvalidBase64CharactersDefect, respectively). When decode is False (the default) the body is returned as a string without decoding the Content-Transfer-Encoding. However, for a Content-Transfer-Encoding of 8bit, an attempt is made to decode the original bytes using the charset specified by the Content-Type header, using the replace error handler. If no charset is specified, or if the charset given is not recognized by the email package, the body is decoded using the default ASCII charset. This is a legacy method. On the EmailMessage class its functionality is replaced by get_content() and iter_parts().

set_payload(payload, charset=None)
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. This is a legacy method. On the EmailMessage class its functionality is replaced by set_content().

set_charset(charset)
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 (the message will not be otherwise modified). Anything else will generate a TypeError. If there is no existing MIME-Version header one will be added. If there is no existing Content-Type header, one will be added with a value of text/plain. Whether the Content-Type header already exists or not, its charset parameter will be set to charset.output_charset. If charset.input_charset and charset.output_charset differ, the payload will be re-encoded to the output_charset. If there is no existing Content-Transfer-Encoding header, then the payload will be transfer-encoded, if needed, using the specified Charset, and a header with the appropriate value will be added. If a Content-Transfer-Encoding header already exists, the payload is assumed to already be correctly encoded using that Content-Transfer-Encoding and is not modified. This is a legacy method. On the EmailMessage class its functionality is replaced by the charset parameter of the email.emailmessage.EmailMessage.set_content() method.

get_charset()
Return the Charset instance associated with the message’s payload. This is a legacy method. On the EmailMessage class it always returns None.
 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. In a model generated from bytes, any header values that (in contravention of the RFCs) contain non-ASCII bytes will, when retrieved through this interface, be represented as Header objects with a charset of unknown-8bit.
__len__()
Return the total number of headers, including duplicates.

__contains__(name)
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'])

__getitem__(name)
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.

__setitem__(name, val)
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!'

__delitem__(name)
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.

keys()
Return a list of all the message’s header field names.

values()
Return a list of all the message’s field values.

items()
Return a list of 2-tuples containing all the message’s field headers and values.

get(name, failobj=None)
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=None)
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. If the value contains non-ASCII characters, it can be specified as a three tuple in the format (CHARSET, LANGUAGE, VALUE), where CHARSET is a string naming the charset to be used to encode the value, LANGUAGE can usually be set to None or the empty string (see RFC 2231 for other possibilities), and VALUE is the string value containing non-ASCII code points. If a three tuple is not passed and the value contains non-ASCII characters, it is automatically encoded in RFC 2231 format using a CHARSET of utf-8 and a LANGUAGE of None. 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"
 An example with non-ASCII characters: msg.add_header('Content-Disposition', 'attachment',
               filename=('iso-8859-1', '', 'Fußballer.ppt'))
 Which produces Content-Disposition: attachment; filename*="iso-8859-1''Fu%DFballer.ppt"

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.

get_content_type()
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.

get_content_maintype()
Return the message’s main content type. This is the maintype part of the string returned by get_content_type().

get_content_subtype()
Return the message’s sub-content type. This is the subtype part of the string returned by get_content_type().

get_default_type()
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_default_type(ctype)
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.

get_params(failobj=None, header='content-type', unquote=True)
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. This is a legacy method. On the EmailMessage class its functionality is replaced by the params property of the individual header objects returned by the header access methods.

get_param(param, failobj=None, header='content-type', unquote=True)
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). 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 when 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. This is a legacy method. On the EmailMessage class its functionality is replaced by the params property of the individual header objects returned by the header access methods.

set_param(param, value, header='Content-Type', requote=True, charset=None, language='', replace=False)
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. If replace is False (the default) the header is moved to the end of the list of headers. If replace is True, the header will be updated in place.  Changed in version 3.4: replace keyword was added.

del_param(param, header='content-type', requote=True)
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_type(type, header='Content-Type', requote=True)
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. This is a legacy method. On the EmailMessage class its functionality is replaced by the make_ and add_ methods.

get_filename(failobj=None)
Return the value of the filename parameter of the Content-Disposition header of the message. If the header does not have a filename parameter, this method falls back to looking for the name parameter on the Content-Type header. If neither is found, or the header is missing, then failobj is returned. The returned string will always be unquoted as per email.utils.unquote().

get_boundary(failobj=None)
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 email.utils.unquote().

set_boundary(boundary)
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.

get_content_charset(failobj=None)
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.

get_charsets(failobj=None)
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.

get_content_disposition()
Return the lowercased value (without parameters) of the message’s Content-Disposition header if it has one, or None. The possible values for this method are inline, attachment or None if the message follows RFC 2183.  New in version 3.5.

walk()
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
text/plain
 walk iterates over the subparts of any part where is_multipart() returns True, even though msg.get_content_maintype() == 'multipart' may return False. We can see this in our example by making use of the _structure debug helper function: >>> for part in msg.walk():
...     print(part.get_content_maintype() == 'multipart',
...           part.is_multipart())
True True
False False
False True
False False
False False
False True
False False
>>> _structure(msg)
multipart/report
    text/plain
    message/delivery-status
        text/plain
        text/plain
    message/rfc822
        text/plain
 Here the message parts are not multiparts, but they do contain subparts. is_multipart() returns True and walk descends into the subparts.
 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. 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.


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. If the value contains non-ASCII characters, it can be specified as a three tuple in the format (CHARSET, LANGUAGE, VALUE), where CHARSET is a string naming the charset to be used to encode the value, LANGUAGE can usually be set to None or the empty string (see RFC 2231 for other possibilities), and VALUE is the string value containing non-ASCII code points. If a three tuple is not passed and the value contains non-ASCII characters, it is automatically encoded in RFC 2231 format using a CHARSET of utf-8 and a LANGUAGE of None. 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"
 An example with non-ASCII characters: msg.add_header('Content-Disposition', 'attachment',
               filename=('iso-8859-1', '', 'Fußballer.ppt'))
 Which produces Content-Disposition: attachment; filename*="iso-8859-1''Fu%DFballer.ppt"


as_bytes(unixfrom=False, policy=None)
Return the entire message flattened as a bytes object. When optional unixfrom is true, the envelope header is included in the returned string. unixfrom defaults to False. The policy argument may be used to override the default policy obtained from the message instance. This can be used to control some of the formatting produced by the method, since the specified policy will be passed to the BytesGenerator. Flattening the message may trigger changes to the Message if defaults need to be filled in to complete the transformation to a string (for example, MIME boundaries may be generated or modified). 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 does not do the mangling of lines that begin with From that is required by the unix mbox format. For more flexibility, instantiate a BytesGenerator instance and use its flatten() method directly. For example: from io import BytesIO
from email.generator import BytesGenerator
fp = BytesIO()
g = BytesGenerator(fp, mangle_from_=True, maxheaderlen=60)
g.flatten(msg)
text = fp.getvalue()
  New in version 3.4.


as_string(unixfrom=False, maxheaderlen=0, policy=None)
Return the entire message flattened as a string. When optional unixfrom is true, the envelope header is included in the returned string. unixfrom defaults to False. For backward compatibility reasons, maxheaderlen defaults to 0, so if you want a different value you must override it explicitly (the value specified for max_line_length in the policy will be ignored by this method). The policy argument may be used to override the default policy obtained from the message instance. This can be used to control some of the formatting produced by the method, since the specified policy will be passed to the Generator. Flattening the message may trigger changes to the Message if defaults need to be filled in to complete the transformation to a string (for example, MIME boundaries may be generated or modified). 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 does not do the mangling of lines that begin with From that is required by the unix mbox format. For more flexibility, instantiate a Generator instance and use its flatten() method directly. For example: from io import StringIO
from email.generator import Generator
fp = StringIO()
g = Generator(fp, mangle_from_=True, maxheaderlen=60)
g.flatten(msg)
text = fp.getvalue()
 If the message object contains binary data that is not encoded according to RFC standards, the non-compliant data will be replaced by unicode “unknown character” code points. (See also as_bytes() and BytesGenerator.)  Changed in version 3.4: the policy keyword argument was added.


attach(payload)
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. This is a legacy method. On the EmailMessage class its functionality is replaced by set_content() and the related make and add methods.


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.


del_param(param, header='content-type', requote=True)
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.


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. 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.


get(name, failobj=None)
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).


get_all(name, failobj=None)
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).


get_boundary(failobj=None)
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 email.utils.unquote().


get_charset()
Return the Charset instance associated with the message’s payload. This is a legacy method. On the EmailMessage class it always returns None.


get_charsets(failobj=None)
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.


get_content_charset(failobj=None)
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.


get_content_disposition()
Return the lowercased value (without parameters) of the message’s Content-Disposition header if it has one, or None. The possible values for this method are inline, attachment or None if the message follows RFC 2183.  New in version 3.5.


get_content_maintype()
Return the message’s main content type. This is the maintype part of the string returned by get_content_type().


get_content_subtype()
Return the message’s sub-content type. This is the subtype part of the string returned by get_content_type().


get_content_type()
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.


get_default_type()
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.


get_filename(failobj=None)
Return the value of the filename parameter of the Content-Disposition header of the message. If the header does not have a filename parameter, this method falls back to looking for the name parameter on the Content-Type header. If neither is found, or the header is missing, then failobj is returned. The returned string will always be unquoted as per email.utils.unquote().


get_param(param, failobj=None, header='content-type', unquote=True)
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). 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 when 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. This is a legacy method. On the EmailMessage class its functionality is replaced by the params property of the individual header objects returned by the header access methods.


get_params(failobj=None, header='content-type', unquote=True)
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. This is a legacy method. On the EmailMessage class its functionality is replaced by the params property of the individual header objects returned by the header access methods.


get_payload(i=None, decode=False)
Return 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, the payload is returned as-is (undecoded). In all cases the returned value is binary data. If the message is a multipart and the decode flag is True, then None is returned. If the payload is base64 and it was not perfectly formed (missing padding, characters outside the base64 alphabet), then an appropriate defect will be added to the message’s defect property (InvalidBase64PaddingDefect or InvalidBase64CharactersDefect, respectively). When decode is False (the default) the body is returned as a string without decoding the Content-Transfer-Encoding. However, for a Content-Transfer-Encoding of 8bit, an attempt is made to decode the original bytes using the charset specified by the Content-Type header, using the replace error handler. If no charset is specified, or if the charset given is not recognized by the email package, the body is decoded using the default ASCII charset. This is a legacy method. On the EmailMessage class its functionality is replaced by get_content() and iter_parts().


get_unixfrom()
Return the message’s envelope header. Defaults to None if the envelope header was never set.


is_multipart()
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 (which might be a CTE encoded binary payload). (Note that is_multipart() returning True does not necessarily mean that “msg.get_content_maintype() == ‘multipart’” will return the True. For example, is_multipart will return True when the Message is of type message/rfc822.)


items()
Return a list of 2-tuples containing all the message’s field headers and values.


keys()
Return a list of all the message’s header field names.


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.


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.


set_boundary(boundary)
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.


set_charset(charset)
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 (the message will not be otherwise modified). Anything else will generate a TypeError. If there is no existing MIME-Version header one will be added. If there is no existing Content-Type header, one will be added with a value of text/plain. Whether the Content-Type header already exists or not, its charset parameter will be set to charset.output_charset. If charset.input_charset and charset.output_charset differ, the payload will be re-encoded to the output_charset. If there is no existing Content-Transfer-Encoding header, then the payload will be transfer-encoded, if needed, using the specified Charset, and a header with the appropriate value will be added. If a Content-Transfer-Encoding header already exists, the payload is assumed to already be correctly encoded using that Content-Transfer-Encoding and is not modified. This is a legacy method. On the EmailMessage class its functionality is replaced by the charset parameter of the email.emailmessage.EmailMessage.set_content() method.


set_default_type(ctype)
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.


set_param(param, value, header='Content-Type', requote=True, charset=None, language='', replace=False)
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. If replace is False (the default) the header is moved to the end of the list of headers. If replace is True, the header will be updated in place.  Changed in version 3.4: replace keyword was added.


set_payload(payload, charset=None)
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. This is a legacy method. On the EmailMessage class its functionality is replaced by set_content().


set_type(type, header='Content-Type', requote=True)
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. This is a legacy method. On the EmailMessage class its functionality is replaced by the make_ and add_ methods.


set_unixfrom(unixfrom)
Set the message’s envelope header to unixfrom, which should be a string.


values()
Return a list of all the message’s field values.


walk()
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
text/plain
 walk iterates over the subparts of any part where is_multipart() returns True, even though msg.get_content_maintype() == 'multipart' may return False. We can see this in our example by making use of the _structure debug helper function: >>> for part in msg.walk():
...     print(part.get_content_maintype() == 'multipart',
...           part.is_multipart())
True True
False False
False True
False False
False False
False True
False False
>>> _structure(msg)
multipart/report
    text/plain
    message/delivery-status
        text/plain
        text/plain
    message/rfc822
        text/plain
 Here the message parts are not multiparts, but they do contain subparts. is_multipart() returns True and walk descends into the subparts.


__bytes__()
Equivalent to as_bytes(). Allows bytes(msg) to produce a bytes object containing the formatted message.  New in version 3.4.


__contains__(name)
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'])


__delitem__(name)
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.


__getitem__(name)
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.


__len__()
Return the total number of headers, including duplicates.


__setitem__(name, val)
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!'


__str__()
Equivalent to as_string(). Allows str(msg) to produce a string containing the formatted message.


class email.message.MIMEPart(policy=default)
This class represents a subpart of a MIME message. It is identical to EmailMessage, except that no MIME-Version headers are added when set_content() is called, since sub-parts do not need their own MIME-Version headers.


email.message_from_binary_file(fp, _class=None, *, policy=policy.compat32)
Return a message object structure tree from an open binary file object. This is equivalent to BytesParser().parse(fp). _class and policy are interpreted as with the BytesParser class constructor.  New in version 3.2.   Changed in version 3.3: Removed the strict argument. Added the policy keyword.


email.message_from_bytes(s, _class=None, *, policy=policy.compat32)
Return a message object structure from a bytes-like object. This is equivalent to BytesParser().parsebytes(s). Optional _class and policy are interpreted as with the BytesParser class constructor.  New in version 3.2.   Changed in version 3.3: Removed the strict argument. Added the policy keyword.


email.message_from_file(fp, _class=None, *, policy=policy.compat32)
Return a message object structure tree from an open file object. This is equivalent to Parser().parse(fp). _class and policy are interpreted as with the Parser class constructor.  Changed in version 3.3: Removed the strict argument. Added the policy keyword.   Changed in version 3.6: _class defaults to the policy message_factory.


email.message_from_string(s, _class=None, *, policy=policy.compat32)
Return a message object structure from a string. This is equivalent to Parser().parsestr(s). _class and policy are interpreted as with the Parser class constructor.  Changed in version 3.3: Removed the strict argument. Added the policy keyword.


class email.mime.application.MIMEApplication(_data, _subtype='octet-stream', _encoder=email.encoders.encode_base64, *, policy=compat32, **_params)
Module: email.mime.application A subclass of MIMENonMultipart, the MIMEApplication class is used to represent MIME message objects of major type application. _data is a string containing the raw byte data. Optional _subtype specifies the MIME subtype and defaults to octet-stream. Optional _encoder is a callable (i.e. function) which will perform the actual encoding of the data for transport. This callable takes one argument, which is the MIMEApplication 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. Optional policy argument defaults to compat32. _params are passed straight through to the base class constructor.  Changed in version 3.6: Added policy keyword-only parameter.


class email.mime.audio.MIMEAudio(_audiodata, _subtype=None, _encoder=email.encoders.encode_base64, *, policy=compat32, **_params)
Module: email.mime.audio 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 argument. 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. Optional policy argument defaults to compat32. _params are passed straight through to the base class constructor.  Changed in version 3.6: Added policy keyword-only parameter.


class email.mime.base.MIMEBase(_maintype, _subtype, *, policy=compat32, **_params)
Module: email.mime.base 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. If policy is specified, (defaults to the compat32 policy) it will be passed to Message. 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).  Changed in version 3.6: Added policy keyword-only parameter.


class email.mime.image.MIMEImage(_imagedata, _subtype=None, _encoder=email.encoders.encode_base64, *, policy=compat32, **_params)
Module: email.mime.image 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 argument. 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. Optional policy argument defaults to compat32. _params are passed straight through to the MIMEBase constructor.  Changed in version 3.6: Added policy keyword-only parameter.


class email.mime.message.MIMEMessage(_msg, _subtype='rfc822', *, policy=compat32)
Module: email.mime.message 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. Optional policy argument defaults to compat32.  Changed in version 3.6: Added policy keyword-only parameter.


class email.mime.multipart.MIMEMultipart(_subtype='mixed', boundary=None, _subparts=None, *, policy=compat32, **_params)
Module: email.mime.multipart 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 (for example, when the message is serialized). _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. Optional policy argument defaults to compat32. Additional parameters for the Content-Type header are taken from the keyword arguments, or passed into the _params argument, which is a keyword dictionary.  Changed in version 3.6: Added policy keyword-only parameter.


class email.mime.nonmultipart.MIMENonMultipart
Module: email.mime.nonmultipart 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.


class email.mime.text.MIMEText(_text, _subtype='plain', _charset=None, *, policy=compat32)
Module: email.mime.text 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 an argument to the MIMENonMultipart constructor; it defaults to us-ascii if the string contains only ascii code points, and utf-8 otherwise. The _charset parameter accepts either a string or a Charset instance. Unless the _charset argument is explicitly set to None, the MIMEText object created will have both a Content-Type header with a charset parameter, and a Content-Transfer-Encoding header. This means that a subsequent set_payload call will not result in an encoded payload, even if a charset is passed in the set_payload command. You can “reset” this behavior by deleting the Content-Transfer-Encoding header, after which a set_payload call will automatically encode the new payload (and add a new Content-Transfer-Encoding header). Optional policy argument defaults to compat32.  Changed in version 3.5: _charset also accepts Charset instances.   Changed in version 3.6: Added policy keyword-only parameter.


class email.parser.BytesFeedParser(_factory=None, *, policy=policy.compat32)
Create a BytesFeedParser instance. Optional _factory is a no-argument callable; if not specified use the message_factory from the policy. Call _factory whenever a new message object is needed. If policy is specified use the rules it specifies to update the representation of the message. If policy is not set, use the compat32 policy, which maintains backward compatibility with the Python 3.2 version of the email package and provides Message as the default factory. All other policies provide EmailMessage as the default _factory. For more information on what else policy controls, see the policy documentation. Note: The policy keyword should always be specified; The default will change to email.policy.default in a future version of Python.  New in version 3.2.   Changed in version 3.3: Added the policy keyword.   Changed in version 3.6: _factory defaults to the policy message_factory.
feed(data)
Feed the parser some more data. data should be a bytes-like object containing one or more lines. The lines can be partial and the parser will stitch such partial lines together properly. The lines can have any of the three common line endings: carriage return, newline, or carriage return and newline (they can even be mixed).

close()
Complete the parsing of all previously fed data and return the root message object. It is undefined what happens if feed() is called after this method has been called.


close()
Complete the parsing of all previously fed data and return the root message object. It is undefined what happens if feed() is called after this method has been called.


feed(data)
Feed the parser some more data. data should be a bytes-like object containing one or more lines. The lines can be partial and the parser will stitch such partial lines together properly. The lines can have any of the three common line endings: carriage return, newline, or carriage return and newline (they can even be mixed).


class email.parser.BytesHeaderParser(_class=None, *, policy=policy.compat32)
Exactly like BytesParser, except that headersonly defaults to True.  New in version 3.3.


class email.parser.BytesParser(_class=None, *, policy=policy.compat32)
Create a BytesParser instance. The _class and policy arguments have the same meaning and semantics as the _factory and policy arguments of BytesFeedParser. Note: The policy keyword should always be specified; The default will change to email.policy.default in a future version of Python.  Changed in version 3.3: Removed the strict argument that was deprecated in 2.4. Added the policy keyword.   Changed in version 3.6: _class defaults to the policy message_factory.
parse(fp, headersonly=False)
Read all the data from the binary file-like object fp, parse the resulting bytes, and return the message object. fp must support both the readline() and the read() methods. The bytes contained in fp must be formatted as a block of RFC 5322 (or, if utf8 is True, RFC 6532) style headers and header continuation lines, optionally preceded by an envelope header. The header block is terminated either by the end of the data or by a blank line. Following the header block is the body of the message (which may contain MIME-encoded subparts, including subparts with a Content-Transfer-Encoding of 8bit). Optional headersonly is a flag specifying whether to stop parsing after reading the headers or not. The default is False, meaning it parses the entire contents of the file.

parsebytes(bytes, headersonly=False)
Similar to the parse() method, except it takes a bytes-like object instead of a file-like object. Calling this method on a bytes-like object is equivalent to wrapping bytes in a BytesIO instance first and calling parse(). Optional headersonly is as with the parse() method.
  New in version 3.2.


parse(fp, headersonly=False)
Read all the data from the binary file-like object fp, parse the resulting bytes, and return the message object. fp must support both the readline() and the read() methods. The bytes contained in fp must be formatted as a block of RFC 5322 (or, if utf8 is True, RFC 6532) style headers and header continuation lines, optionally preceded by an envelope header. The header block is terminated either by the end of the data or by a blank line. Following the header block is the body of the message (which may contain MIME-encoded subparts, including subparts with a Content-Transfer-Encoding of 8bit). Optional headersonly is a flag specifying whether to stop parsing after reading the headers or not. The default is False, meaning it parses the entire contents of the file.


parsebytes(bytes, headersonly=False)
Similar to the parse() method, except it takes a bytes-like object instead of a file-like object. Calling this method on a bytes-like object is equivalent to wrapping bytes in a BytesIO instance first and calling parse(). Optional headersonly is as with the parse() method.


class email.parser.FeedParser(_factory=None, *, policy=policy.compat32)
Works like BytesFeedParser except that the input to the feed() method must be a string. This is of limited utility, since the only way for such a message to be valid is for it to contain only ASCII text or, if utf8 is True, no binary attachments.  Changed in version 3.3: Added the policy keyword.


class email.parser.HeaderParser(_class=None, *, policy=policy.compat32)
Exactly like Parser, except that headersonly defaults to True.


class email.parser.Parser(_class=None, *, policy=policy.compat32)
This class is parallel to BytesParser, but handles string input.  Changed in version 3.3: Removed the strict argument. Added the policy keyword.   Changed in version 3.6: _class defaults to the policy message_factory.
parse(fp, headersonly=False)
Read all the data from the text-mode file-like object fp, parse the resulting text, and return the root message object. fp must support both the readline() and the read() methods on file-like objects. Other than the text mode requirement, this method operates like BytesParser.parse().

parsestr(text, headersonly=False)
Similar to the parse() method, except it takes a string object instead of a file-like object. Calling this method on a string is equivalent to wrapping text in a StringIO instance first and calling parse(). Optional headersonly is as with the parse() method.


parse(fp, headersonly=False)
Read all the data from the text-mode file-like object fp, parse the resulting text, and return the root message object. fp must support both the readline() and the read() methods on file-like objects. Other than the text mode requirement, this method operates like BytesParser.parse().


parsestr(text, headersonly=False)
Similar to the parse() method, except it takes a string object instead of a file-like object. Calling this method on a string is equivalent to wrapping text in a StringIO instance first and calling parse(). Optional headersonly is as with the parse() method.


email.policy.compat32
An instance of Compat32, providing backward compatibility with the behavior of the email package in Python 3.2.


class email.policy.Compat32(**kw)
This concrete Policy is the backward compatibility policy. It replicates the behavior of the email package in Python 3.2. The policy module also defines an instance of this class, compat32, that is used as the default policy. Thus the default behavior of the email package is to maintain compatibility with Python 3.2. The following attributes have values that are different from the Policy default:
mangle_from_
The default is True.
 The class provides the following concrete implementations of the abstract methods of Policy:
header_source_parse(sourcelines)
The name is parsed as everything up to the ‘:’ and returned unmodified. The value is determined by stripping leading whitespace off the remainder of the first line, joining all subsequent lines together, and stripping any trailing carriage return or linefeed characters.

header_store_parse(name, value)
The name and value are returned unmodified.

header_fetch_parse(name, value)
If the value contains binary data, it is converted into a Header object using the unknown-8bit charset. Otherwise it is returned unmodified.

fold(name, value)
Headers are folded using the Header folding algorithm, which preserves existing line breaks in the value, and wraps each resulting line to the max_line_length. Non-ASCII binary data are CTE encoded using the unknown-8bit charset.

fold_binary(name, value)
Headers are folded using the Header folding algorithm, which preserves existing line breaks in the value, and wraps each resulting line to the max_line_length. If cte_type is 7bit, non-ascii binary data is CTE encoded using the unknown-8bit charset. Otherwise the original source header is used, with its existing line breaks and any (RFC invalid) binary data it may contain.


fold(name, value)
Headers are folded using the Header folding algorithm, which preserves existing line breaks in the value, and wraps each resulting line to the max_line_length. Non-ASCII binary data are CTE encoded using the unknown-8bit charset.


fold_binary(name, value)
Headers are folded using the Header folding algorithm, which preserves existing line breaks in the value, and wraps each resulting line to the max_line_length. If cte_type is 7bit, non-ascii binary data is CTE encoded using the unknown-8bit charset. Otherwise the original source header is used, with its existing line breaks and any (RFC invalid) binary data it may contain.


header_fetch_parse(name, value)
If the value contains binary data, it is converted into a Header object using the unknown-8bit charset. Otherwise it is returned unmodified.


header_source_parse(sourcelines)
The name is parsed as everything up to the ‘:’ and returned unmodified. The value is determined by stripping leading whitespace off the remainder of the first line, joining all subsequent lines together, and stripping any trailing carriage return or linefeed characters.


header_store_parse(name, value)
The name and value are returned unmodified.


email.policy.default
An instance of EmailPolicy with all defaults unchanged. This policy uses the standard Python \n line endings rather than the RFC-correct \r\n.


class email.policy.EmailPolicy(**kw)
This concrete Policy provides behavior that is intended to be fully compliant with the current email RFCs. These include (but are not limited to) RFC 5322, RFC 2047, and the current MIME RFCs. This policy adds new header parsing and folding algorithms. Instead of simple strings, headers are str subclasses with attributes that depend on the type of the field. The parsing and folding algorithm fully implement RFC 2047 and RFC 5322. The default value for the message_factory attribute is EmailMessage. In addition to the settable attributes listed above that apply to all policies, this policy adds the following additional attributes:  New in version 3.6: 1
utf8
If False, follow RFC 5322, supporting non-ASCII characters in headers by encoding them as “encoded words”. If True, follow RFC 6532 and use utf-8 encoding for headers. Messages formatted in this way may be passed to SMTP servers that support the SMTPUTF8 extension (RFC 6531).

refold_source
If the value for a header in the Message object originated from a parser (as opposed to being set by a program), this attribute indicates whether or not a generator should refold that value when transforming the message back into serialized form. The possible values are:
none all source values use original folding
long source values that have any line that is longer than max_line_length will be refolded
all all values are refolded.   The default is long.

header_factory
A callable that takes two arguments, name and value, where name is a header field name and value is an unfolded header field value, and returns a string subclass that represents that header. A default header_factory (see headerregistry) is provided that supports custom parsing for the various address and date RFC 5322 header field types, and the major MIME header field stypes. Support for additional custom parsing will be added in the future.

content_manager
An object with at least two methods: get_content and set_content. When the get_content() or set_content() method of an EmailMessage object is called, it calls the corresponding method of this object, passing it the message object as its first argument, and any arguments or keywords that were passed to it as additional arguments. By default content_manager is set to raw_data_manager.  New in version 3.4.
 The class provides the following concrete implementations of the abstract methods of Policy:
header_max_count(name)
Returns the value of the max_count attribute of the specialized class used to represent the header with the given name.

header_source_parse(sourcelines)
The name is parsed as everything up to the ‘:’ and returned unmodified. The value is determined by stripping leading whitespace off the remainder of the first line, joining all subsequent lines together, and stripping any trailing carriage return or linefeed characters.

header_store_parse(name, value)
The name is returned unchanged. If the input value has a name attribute and it matches name ignoring case, the value is returned unchanged. Otherwise the name and value are passed to header_factory, and the resulting header object is returned as the value. In this case a ValueError is raised if the input value contains CR or LF characters.

header_fetch_parse(name, value)
If the value has a name attribute, it is returned to unmodified. Otherwise the name, and the value with any CR or LF characters removed, are passed to the header_factory, and the resulting header object is returned. Any surrogateescaped bytes get turned into the unicode unknown-character glyph.

fold(name, value)
Header folding is controlled by the refold_source policy setting. A value is considered to be a ‘source value’ if and only if it does not have a name attribute (having a name attribute means it is a header object of some sort). If a source value needs to be refolded according to the policy, it is converted into a header object by passing the name and the value with any CR and LF characters removed to the header_factory. Folding of a header object is done by calling its fold method with the current policy. Source values are split into lines using splitlines(). If the value is not to be refolded, the lines are rejoined using the linesep from the policy and returned. The exception is lines containing non-ascii binary data. In that case the value is refolded regardless of the refold_source setting, which causes the binary data to be CTE encoded using the unknown-8bit charset.

fold_binary(name, value)
The same as fold() if cte_type is 7bit, except that the returned value is bytes. If cte_type is 8bit, non-ASCII binary data is converted back into bytes. Headers with binary data are not refolded, regardless of the refold_header setting, since there is no way to know whether the binary data consists of single byte characters or multibyte characters.


content_manager
An object with at least two methods: get_content and set_content. When the get_content() or set_content() method of an EmailMessage object is called, it calls the corresponding method of this object, passing it the message object as its first argument, and any arguments or keywords that were passed to it as additional arguments. By default content_manager is set to raw_data_manager.  New in version 3.4.


fold(name, value)
Header folding is controlled by the refold_source policy setting. A value is considered to be a ‘source value’ if and only if it does not have a name attribute (having a name attribute means it is a header object of some sort). If a source value needs to be refolded according to the policy, it is converted into a header object by passing the name and the value with any CR and LF characters removed to the header_factory. Folding of a header object is done by calling its fold method with the current policy. Source values are split into lines using splitlines(). If the value is not to be refolded, the lines are rejoined using the linesep from the policy and returned. The exception is lines containing non-ascii binary data. In that case the value is refolded regardless of the refold_source setting, which causes the binary data to be CTE encoded using the unknown-8bit charset.


fold_binary(name, value)
The same as fold() if cte_type is 7bit, except that the returned value is bytes. If cte_type is 8bit, non-ASCII binary data is converted back into bytes. Headers with binary data are not refolded, regardless of the refold_header setting, since there is no way to know whether the binary data consists of single byte characters or multibyte characters.


header_factory
A callable that takes two arguments, name and value, where name is a header field name and value is an unfolded header field value, and returns a string subclass that represents that header. A default header_factory (see headerregistry) is provided that supports custom parsing for the various address and date RFC 5322 header field types, and the major MIME header field stypes. Support for additional custom parsing will be added in the future.


header_fetch_parse(name, value)
If the value has a name attribute, it is returned to unmodified. Otherwise the name, and the value with any CR or LF characters removed, are passed to the header_factory, and the resulting header object is returned. Any surrogateescaped bytes get turned into the unicode unknown-character glyph.


header_max_count(name)
Returns the value of the max_count attribute of the specialized class used to represent the header with the given name.


header_store_parse(name, value)
The name is returned unchanged. If the input value has a name attribute and it matches name ignoring case, the value is returned unchanged. Otherwise the name and value are passed to header_factory, and the resulting header object is returned as the value. In this case a ValueError is raised if the input value contains CR or LF characters.


refold_source
If the value for a header in the Message object originated from a parser (as opposed to being set by a program), this attribute indicates whether or not a generator should refold that value when transforming the message back into serialized form. The possible values are:
none all source values use original folding
long source values that have any line that is longer than max_line_length will be refolded
all all values are refolded.   The default is long.


utf8
If False, follow RFC 5322, supporting non-ASCII characters in headers by encoding them as “encoded words”. If True, follow RFC 6532 and use utf-8 encoding for headers. Messages formatted in this way may be passed to SMTP servers that support the SMTPUTF8 extension (RFC 6531).


email.policy.HTTP
Suitable for serializing headers with for use in HTTP traffic. Like SMTP except that max_line_length is set to None (unlimited).