mailer.py

#coding: UTF8
"""
mailer module

Simple front end to the smtplib and email modules,
to simplify sending email.

A lot of this code was taken from the online examples in the
email module documentation:
http://docs.python.org/library/email-examples.html

Released under MIT license.

Version 0.5 is based on a patch by Douglas Mayle

Sample code:

    import mailer
    
    message = mailer.Message()
    message.From = "me@example.com"
    message.To = "you@example.com"
    message.Subject = "My Vacation"
    message.Body = open("letter.txt", "rb").read()
    message.attach("picture.jpg")
    
    sender = mailer.Mailer('mail.example.com')
    sender.send(message)

"""
import smtplib

# this is to support name changes
# from version 2.4 to version 2.5
try:
    from email import encoders
    from email.header import make_header
    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
except ImportError:
    from email import Encoders as encoders
    from email.Header import make_header
    from email.MIMEMessage import Message
    from email.MIMEAudio import MIMEAudio
    from email.MIMEBase import MIMEBase
    from email.MIMEImage import MIMEImage
    from email.MIMEMultipart import MIMEMultipart
    from email.MIMEText import MIMEText

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

from os import path

__version__ = "0.5"
__author__ = "Ryan Ginstrom"
__license__ = "MIT"
__description__ = "A module to send email simply in Python"

class Mailer(object):
    """
    Represents an SMTP connection.
    
    Use login() to log in with a username and password.
    """

    def __init__(self, host="localhost", port=0):
        self.host = host
        self.port = port
        self._usr = None
        self._pwd = None
    
    def login(self, usr, pwd):
        self._usr = usr
        self._pwd = pwd

    def send(self, msg):
        """
        Send one message or a sequence of messages.

        Every time you call send, the mailer creates a new
        connection, so if you have several emails to send, pass
        them as a list:
        mailer.send([msg1, msg2, msg3])
        """
        server = smtplib.SMTP(self.host, self.port)

        if self._usr and self._pwd:
            server.login(self._usr, self._pwd)

        try:
            num_msgs = len(msg)
            for m in msg:
                self._send(server, m)
        except TypeError:
            self._send(server, msg)

        server.quit()
    
    def _send(self, server, msg):
        """
        Sends a single message using the server
        we created in send()
        """
        me = msg.From
        if isinstance(msg.To, basestring):
            you = [msg.To]
        else:
            you = list(msg.To)
        server.sendmail(me, you, msg.as_string())

class Message(object):
    """
    Represents an email message.
    
    Set the To, From, Subject, and Body attributes as plain-text strings.
    Optionally, set the Html attribute to send an HTML email, or use the
    attach() method to attach files.
    
    Use the charset property to send messages using other than us-ascii
    
    If you specify an attachments argument, it should be a list of
    attachment filenames: ["file1.txt", "file2.txt"]
    
    `To` should be a string for a single address, and a sequence
    of strings for multiple recipients (castable to list)
    
    Send using the Mailer class.
    """

    def __init__(self, To=None, From=None, Subject=None, Body=None, Html=None,
                 attachments=None, charset=None):
        self.attachments = []
        if attachments:
            for attachment in attachments:
                if isinstance(attachment, basestring):
                    self.attachments.append((attachment, None))
                else:
                    try:
                        filename, cid = attachment
                    except (TypeError, IndexError):
                        self.attachments.append((attachment, None))
                    else:
                        self.attachments.append((filename, cid))
        self.To = To
        """string or iterable"""
        self.From = From
        """string"""
        self.Subject = Subject
        self.Body = Body
        self.Html = Html
        self.charset = charset or 'us-ascii'

    def as_string(self):
        """Get the email as a string to send in the mailer"""

        if not self.attachments:
            return self._plaintext()
        else:
            return self._multipart()
    
    def _plaintext(self):
        """Plain text email with no attachments"""

        if not self.Html:
            msg = MIMEText(self.Body, 'plain', self.charset)
        else:
            msg  = self._with_html()

        self._set_info(msg)
        return msg.as_string()
            
    def _with_html(self):
        """There's an html part"""

        outer = MIMEMultipart('alternative')
        
        part1 = MIMEText(self.Body, 'plain', self.charset)
        part2 = MIMEText(self.Html, 'html', self.charset)

        outer.attach(part1)
        outer.attach(part2)
        
        return outer

    def _set_info(self, msg):
        if self.charset == 'us-ascii':
            msg['Subject'] = self.Subject
        else:
            subject = unicode(self.Subject, self.charset)
            msg['Subject'] = str(make_header([(subject, self.charset)]))
        msg['From'] = self.From
        if isinstance(self.To, basestring):
            msg['To'] = self.To
        else:
            self.To = list(self.To)
            msg['To'] = ", ".join(self.To)

    def _multipart(self):
        """The email has attachments"""

        msg = MIMEMultipart('related')

        if self.Html:
            outer = MIMEMultipart('alternative')
            
            part1 = MIMEText(self.Body, 'plain', self.charset)
            part1.add_header('Content-Disposition', 'inline')

            part2 = MIMEText(self.Html, 'html', self.charset)
            part2.add_header('Content-Disposition', 'inline')

            outer.attach(part1)
            outer.attach(part2)
            msg.attach(outer)
        else:
            msg.attach(MIMEText(self.Body, 'plain', self.charset))

        self._set_info(msg)
        msg.preamble = self.Subject

        for filename, cid in self.attachments:
            self._add_attachment(msg, filename, cid)

        return msg.as_string()

    def _add_attachment(self, outer, filename, cid):
        ctype, encoding = mimetypes.guess_type(filename)
        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)
        fp = open(filename, 'rb')
        if maintype == 'text':
            # Note: we should handle calculating the charset
            msg = MIMEText(fp.read(), _subtype=subtype)
        elif maintype == 'image':
            msg = MIMEImage(fp.read(), _subtype=subtype)
        elif maintype == 'audio':
            msg = MIMEAudio(fp.read(), _subtype=subtype)
        else:
            msg = MIMEBase(maintype, subtype)
            msg.set_payload(fp.read())
            # Encode the payload using Base64
            encoders.encode_base64(msg)
        fp.close()

        # Set the content-ID header
        if cid:
            msg.add_header('Content-ID', '<%s>' % cid)
            msg.add_header('Content-Disposition', 'inline')
        else:
            # Set the filename parameter
            msg.add_header('Content-Disposition', 'attachment', filename=path.basename(filename))
        outer.attach(msg)

    def attach(self, filename, cid=None):
        """
        Attach a file to the email. Specify the name of the file;
        Message will figure out the MIME type and load the file.
        """
        
        self.attachments.append((filename, cid))