# 18.1.11. `email`: 使用例

ここでは `email` パッケージを使って電子メールメッセージを読む・書く・送信するいくつかの例を紹介します。より複雑な MIME メッセージについても扱います。

最初に、テキスト形式の単純なメッセージを作成・送信する方法です:

    # Import smtplib for the actual sending function
    import smtplib

    # Import the email modules we'll need
    from email.mime.text import MIMEText

    # Open a plain text file for reading.  For this example, assume that
    # the text file contains only ASCII characters.
    fp = open(textfile, 'rb')
    # Create a text/plain message
    msg = MIMEText(fp.read())
    fp.close()

    # me == the sender's email address
    # you == the recipient's email address
    msg['Subject'] = 'The contents of %s' % textfile
    msg['From'] = me
    msg['To'] = you

    # Send the message via our own SMTP server, but don't include the
    # envelope header.
    s = smtplib.SMTP('localhost')
    s.sendmail(me, [you], msg.as_string())
    s.quit()

Parser() クラスの parse(filename) か parsestr(message_as_string) メソッドを使って簡単に RFC822 ヘッダの解析ができます:

    # Import the email modules we'll need
    from email.parser import Parser

    #  If the e-mail headers are in a file, uncomment this line:
    #headers = Parser().parse(open(messagefile, 'r'))

    #  Or for parsing headers in a string, use:
    headers = Parser().parsestr('From: <user@example.com>\n'
            'To: <someone_else@example.com>\n'
            'Subject: Test message\n'
            '\n'
            'Body would go here\n')

    #  Now the header items can be accessed as a dictionary:
    print 'To: %s' % headers['to']
    print 'From: %s' % headers['from']
    print 'Subject: %s' % headers['subject']

つぎに、あるディレクトリ内にある何枚かの家族写真をひとつの MIME メッセージに収めて送信する例です:

    # Import smtplib for the actual sending function
    import smtplib

    # Here are the email package modules we'll need
    from email.mime.image import MIMEImage
    from email.mime.multipart import MIMEMultipart

    COMMASPACE = ', '

    # Create the container (outer) email message.
    msg = MIMEMultipart()
    msg['Subject'] = 'Our family reunion'
    # me == the sender's email address
    # family = the list of all recipients' email addresses
    msg['From'] = me
    msg['To'] = COMMASPACE.join(family)
    msg.preamble = 'Our family reunion'

    # Assume we know that the image files are all in PNG format
    for file in pngfiles:
        # Open the files in binary mode.  Let the MIMEImage class automatically
        # guess the specific image type.
        fp = open(file, 'rb')
        img = MIMEImage(fp.read())
        fp.close()
        msg.attach(img)

    # Send the email via our own SMTP server.
    s = smtplib.SMTP('localhost')
    s.sendmail(me, family, msg.as_string())
    s.quit()

つぎはあるディレクトリに含まれている内容全体をひとつの電子メールメッセージとして送信するやり方です: [1]

    #!/usr/bin/env python

    """Send the contents of a directory as a MIME message."""

    import os
    import sys
    import smtplib
    # For guessing MIME type based on file name extension
    import mimetypes

    from optparse import OptionParser

    from email import encoders
    from email.message import Message
    from email.mime.audio import MIMEAudio
    from email.mime.base import MIMEBase
    from email.mime.image import MIMEImage
    from email.mime.multipart import MIMEMultipart
    from email.mime.text import MIMEText

    COMMASPACE = ', '

    def main():
        parser = OptionParser(usage="""\
    Send the contents of a directory as a MIME message.

    Usage: %prog [options]

    Unless the -o option is given, the email is sent by forwarding to your local
    SMTP server, which then does the normal delivery process.  Your local machine
    must be running an SMTP server.
    """)
        parser.add_option('-d', '--directory',
                          type='string', action='store',
                          help="""Mail the contents of the specified directory,
                          otherwise use the current directory.  Only the regular
                          files in the directory are sent, and we don't recurse to
                          subdirectories.""")
        parser.add_option('-o', '--output',
                          type='string', action='store', metavar='FILE',
                          help="""Print the composed message to FILE instead of
                          sending the message to the SMTP server.""")
        parser.add_option('-s', '--sender',
                          type='string', action='store', metavar='SENDER',
                          help='The value of the From: header (required)')
        parser.add_option('-r', '--recipient',
                          type='string', action='append', metavar='RECIPIENT',
                          default=[], dest='recipients',
                          help='A To: header value (at least one required)')
        opts, args = parser.parse_args()
        if not opts.sender or not opts.recipients:
            parser.print_help()
            sys.exit(1)
        directory = opts.directory
        if not directory:
            directory = '.'
        # Create the enclosing (outer) message
        outer = MIMEMultipart()
        outer['Subject'] = 'Contents of directory %s' % os.path.abspath(directory)
        outer['To'] = COMMASPACE.join(opts.recipients)
        outer['From'] = opts.sender
        outer.preamble = 'You will not see this in a MIME-aware mail reader.\n'

        for filename in os.listdir(directory):
            path = os.path.join(directory, filename)
            if not os.path.isfile(path):
                continue
            # Guess the content type based on the file's extension.  Encoding
            # will be ignored, although we should check for simple things like
            # gzip'd or compressed files.
            ctype, encoding = mimetypes.guess_type(path)
            if ctype is None or encoding is not None:
                # No guess could be made, or the file is encoded (compressed), so
                # use a generic bag-of-bits type.
                ctype = 'application/octet-stream'
            maintype, subtype = ctype.split('/', 1)
            if maintype == 'text':
                fp = open(path)
                # Note: we should handle calculating the charset
                msg = MIMEText(fp.read(), _subtype=subtype)
                fp.close()
            elif maintype == 'image':
                fp = open(path, 'rb')
                msg = MIMEImage(fp.read(), _subtype=subtype)
                fp.close()
            elif maintype == 'audio':
                fp = open(path, 'rb')
                msg = MIMEAudio(fp.read(), _subtype=subtype)
                fp.close()
            else:
                fp = open(path, 'rb')
                msg = MIMEBase(maintype, subtype)
                msg.set_payload(fp.read())
                fp.close()
                # Encode the payload using Base64
                encoders.encode_base64(msg)
            # Set the filename parameter
            msg.add_header('Content-Disposition', 'attachment', filename=filename)
            outer.attach(msg)
        # Now send or store the message
        composed = outer.as_string()
        if opts.output:
            fp = open(opts.output, 'w')
            fp.write(composed)
            fp.close()
        else:
            s = smtplib.SMTP('localhost')
            s.sendmail(opts.sender, opts.recipients, composed)
            s.quit()

    if __name__ == '__main__':
        main()

つぎに、上のような MIME メッセージをどうやって展開してひとつのディレクトリ上の複数ファイルにするかを示します:

    #!/usr/bin/env python

    """Unpack a MIME message into a directory of files."""

    import os
    import sys
    import email
    import errno
    import mimetypes

    from optparse import OptionParser

    def main():
        parser = OptionParser(usage="""\
    Unpack a MIME message into a directory of files.

    Usage: %prog [options] msgfile
    """)
        parser.add_option('-d', '--directory',
                          type='string', action='store',
                          help="""Unpack the MIME message into the named
                          directory, which will be created if it doesn't already
                          exist.""")
        opts, args = parser.parse_args()
        if not opts.directory:
            parser.print_help()
            sys.exit(1)

        try:
            msgfile = args[0]
        except IndexError:
            parser.print_help()
            sys.exit(1)

        try:
            os.mkdir(opts.directory)
        except OSError as e:
            # Ignore directory exists error
            if e.errno != errno.EEXIST:
                raise

        fp = open(msgfile)
        msg = email.message_from_file(fp)
        fp.close()

        counter = 1
        for part in msg.walk():
            # multipart/* are just containers
            if part.get_content_maintype() == 'multipart':
                continue
            # Applications should really sanitize the given filename so that an
            # email message can't be used to overwrite important files
            filename = part.get_filename()
            if not filename:
                ext = mimetypes.guess_extension(part.get_content_type())
                if not ext:
                    # Use a generic bag-of-bits extension
                    ext = '.bin'
                filename = 'part-%03d%s' % (counter, ext)
            counter += 1
            fp = open(os.path.join(opts.directory, filename), 'wb')
            fp.write(part.get_payload(decode=True))
            fp.close()

    if __name__ == '__main__':
        main()

つぎの例は、HTML メッセージを代替プレーンテキスト版付きで作るやりかたです: [2]

    #!/usr/bin/env python

    import smtplib

    from email.mime.multipart import MIMEMultipart
    from email.mime.text import MIMEText

    # me == my email address
    # you == recipient's email address
    me = "my@email.com"
    you = "your@email.com"

    # Create message container - the correct MIME type is multipart/alternative.
    msg = MIMEMultipart('alternative')
    msg['Subject'] = "Link"
    msg['From'] = me
    msg['To'] = you

    # Create the body of the message (a plain-text and an HTML version).
    text = "Hi!\nHow are you?\nHere is the link you wanted:\nhttps://www.python.org"
    html = """\
    <html>
      <head></head>
      <body>
        <p>Hi!<br>
           How are you?<br>
           Here is the <a href="https://www.python.org">link</a> you wanted.
        </p>
      </body>
    </html>
    """

    # Record the MIME types of both parts - text/plain and text/html.
    part1 = MIMEText(text, 'plain')
    part2 = MIMEText(html, 'html')

    # Attach parts into message container.
    # According to RFC 2046, the last part of a multipart message, in this case
    # the HTML message, is best and preferred.
    msg.attach(part1)
    msg.attach(part2)

    # Send the message via local SMTP server.
    s = smtplib.SMTP('localhost')
    # sendmail function takes 3 arguments: sender's address, recipient's address
    # and message to send - here it is sent as one string.
    s.sendmail(me, you, msg.as_string())
    s.quit()

注記

[1] | 最初の思いつきと用例は Matthew Dixon Cowles のおかげです。

[2] | Martin Matejek が教えてくれました。