Source code: Lib/email/iterators.py

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Iterating over a message object tree is fairly easy with the Message.walk method. The email.iterators module provides some useful higher level iterations over message object trees.

email.iterators.body_line_iterator(msg, decode=False)

This iterates over all the payloads in all the subparts of msg, returning the string payloads line-by-line. It skips over all the subpart headers, and it skips over any subpart with a payload that isn’t a Python string. This is somewhat equivalent to reading the flat text representation of the message from a file using readline(), skipping over all the intervening headers.

Optional decode is passed through to Message.get_payload.

email.iterators.typed_subpart_iterator(msg, maintype='text', subtype=None)

This iterates over all the subparts of msg, returning only those subparts that match the MIME type specified by maintype and subtype.

Note that subtype is optional; if omitted, then subpart MIME type matching is done only with the main type. maintype is optional too; it defaults to text.

Thus, by default typed_subpart_iterator() returns each subpart that has a MIME type of text/*.

The following function has been added as a useful debugging tool. It should not be considered part of the supported public interface for the package.

email.iterators._structure(msg, fp=None, level=0, include_default=False)

Prints an indented representation of the content types of the message object structure. For example:

>>> msg = email.message_from_file(somefile)
>>> _structure(msg)
multipart/mixed
    text/plain
    text/plain
    multipart/digest
        message/rfc822
            text/plain
        message/rfc822
            text/plain
        message/rfc822
            text/plain
        message/rfc822
            text/plain
        message/rfc822
            text/plain
    text/plain

Optional fp is a file-like object to print the output to. It must be suitable for Python’s print() function. level is used internally. include_default, if true, prints the default type as well.