# `!email.iterators`: Iterators

<div class="module" data-synopsis="Iterate over a  message object tree.">

email.iterators

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**Source code:** `Lib/email/iterators.py`

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

<div class="function">

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 `~io.TextIOBase.readline`, skipping over all the intervening headers.

Optional *decode* is passed through to `Message.get_payload
<email.message.Message.get_payload>`.

</div>

<div class="function">

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/\*`.

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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.

<div class="function">

<span id="structure">structure</span>(msg, fp=None, level=0, include_default=False)

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

<div class="testsetup">

import email from email.iterators import <span id="structure">structure</span> somefile = open('../Lib/test/test_email/data/msg_02.txt')

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<div class="doctest">

\>\>\> msg = email.message_from_file(somefile) \>\>\> <span id="structure">structure</span>(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

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<div class="testcleanup">

somefile.close()

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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.

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