email
— An email and MIME handling package¶
Source code: Lib/email/__init__.py
The email
package is a library for managing email messages. It is
specifically not designed to do any sending of email messages to SMTP
(RFC 2821), NNTP, or other servers; those are functions of modules such as
smtplib
. The email
package attempts to be as
RFC-compliant as possible, supporting RFC 5322 and RFC 6532, as well as
such MIME-related RFCs as RFC 2045, RFC 2046, RFC 2047, RFC 2183,
and RFC 2231.
The overall structure of the email package can be divided into three major components, plus a fourth component that controls the behavior of the other components.
The central component of the package is an “object model” that represents email
messages. An application interacts with the package primarily through the
object model interface defined in the message
sub-module. The
application can use this API to ask questions about an existing email, to
construct a new email, or to add or remove email subcomponents that themselves
use the same object model interface. That is, following the nature of email
messages and their MIME subcomponents, the email object model is a tree
structure of objects that all provide the EmailMessage
API.
The other two major components of the package are the parser
and
the generator
. The parser takes the serialized version of an
email message (a stream of bytes) and converts it into a tree of
EmailMessage
objects. The generator takes an
EmailMessage
and turns it back into a serialized byte
stream. (The parser and generator also handle streams of text characters, but
this usage is discouraged as it is too easy to end up with messages that are
not valid in one way or another.)
The control component is the policy
module. Every
EmailMessage
, every generator
, and every
parser
has an associated policy
object that
controls its behavior. Usually an application only needs to specify the policy
when an EmailMessage
is created, either by directly
instantiating an EmailMessage
to create a new email,
or by parsing an input stream using a parser
. But the policy can
be changed when the message is serialized using a generator
.
This allows, for example, a generic email message to be parsed from disk, but
to serialize it using standard SMTP settings when sending it to an email
server.
The email package does its best to hide the details of the various governing RFCs from the application. Conceptually the application should be able to treat the email message as a structured tree of unicode text and binary attachments, without having to worry about how these are represented when serialized. In practice, however, it is often necessary to be aware of at least some of the rules governing MIME messages and their structure, specifically the names and nature of the MIME “content types” and how they identify multipart documents. For the most part this knowledge should only be required for more complex applications, and even then it should only be the high level structure in question, and not the details of how those structures are represented. Since MIME content types are used widely in modern internet software (not just email), this will be a familiar concept to many programmers.
The following sections describe the functionality of the email
package.
We start with the message
object model, which is the primary
interface an application will use, and follow that with the
parser
and generator
components. Then we cover the
policy
controls, which completes the treatment of the main
components of the library.
The next three sections cover the exceptions the package may raise and the
defects (non-compliance with the RFCs) that the parser
may
detect. Then we cover the headerregistry
and the
contentmanager
sub-components, which provide tools for doing more
detailed manipulation of headers and payloads, respectively. Both of these
components contain features relevant to consuming and producing non-trivial
messages, but also document their extensibility APIs, which will be of interest
to advanced applications.
Following those is a set of examples of using the fundamental parts of the APIs covered in the preceding sections.
The foregoing represent the modern (unicode friendly) API of the email package.
The remaining sections, starting with the Message
class, cover the legacy compat32
API that deals much more
directly with the details of how email messages are represented. The
compat32
API does not hide the details of the RFCs from
the application, but for applications that need to operate at that level, they
can be useful tools. This documentation is also relevant for applications that
are still using the compat32
API for backward
compatibility reasons.
Changed in version 3.6: Docs reorganized and rewritten to promote the new
EmailMessage
/EmailPolicy
API.
Contents of the email
package documentation:
email.message
: Representing an email messageemail.parser
: Parsing email messagesemail.generator
: Generating MIME documentsemail.policy
: Policy Objectsemail.errors
: Exception and Defect classesemail.headerregistry
: Custom Header Objectsemail.contentmanager
: Managing MIME Contentemail
: Examples
Legacy API:
email.message.Message
: Representing an email message using thecompat32
APIemail.mime
: Creating email and MIME objects from scratchemail.header
: Internationalized headersemail.charset
: Representing character setsemail.encoders
: Encodersemail.utils
: Miscellaneous utilitiesemail.iterators
: Iterators