Este script permite enviar emails a través de GMail. Los emails pueden tener texto plano, HTML y archivos adjuntos (todos opcionales).

Nota: el script lo escribí originalmente en inglés. Debería entenderse, pero pienso traducirlo cuando tenga algo más de tiempo.

Archivo: GmailMail.py

#!/usr/bin/env python

# requires Python >= 2.5
import smtplib
from email.mime.multipart import MIMEMultipart
from email.mime.base import MIMEBase
from email.mime.text import MIMEText
from email.mime.audio import MIMEAudio
from email.mime.image import MIMEImage
from email.encoders import encode_base64
from mimetypes import guess_type
from os.path import basename

class GmailMail():
    def __init__(self, gmail_user, gmail_pwd):
        """
        Prepares an instance with basic authentication

        """
        self.gmail_user = gmail_user
        self.gmail_pwd = gmail_pwd

    def getAttachment(self, path, charset='ASCII'):
        contentType, encoding = guess_type(path)

        if contentType is None or encoding is not None:
            contentType = 'application/octet-stream'

        mainType, subType = contentType.split('/', 1)
        _file = open(path, 'rb')

        if mainType == 'text':
            attachment = MIMEText(_file.read(), subType, charset)
        elif mainType == 'message':
            attachment = email.message_from_file(_file)
        elif mainType == 'image':
            attachment = MIMEImage(_file.read(), _subType=subType)
        elif mainType == 'audio':
            attachment = MIMEAudio(_file.read(), _subType=subType)
        else:
            attachment = MIMEBase(mainType, subType)
            attachment.set_payload(_file.read())
            encode_base64(attachment)

        _file.close()

        attachment.add_header('Content-Disposition', 'attachment',
            filename=basename(path))

        return attachment

    def send(self, to, subject, text=u"", html=None, attachments=None, charset="iso-8859-15"):
        """
        Sends an email through Gmail using the authentication
        given to this instance.

        If given, attachments must be a list of paths pointing
        to the files we want to include.

        This script does not embed inline content (multipart/related)

        """
        if charset in ['utf8','utf-8']: #bug?
            from email.charset import add_charset, SHORTEST
            add_charset('utf-8', SHORTEST, None, None)

        if isinstance(text, unicode):
            text = text.encode(charset, 'replace')

        if isinstance(html, unicode):
            html = html.encode(charset, 'replace')

        if attachments is None:
            attachments = []

        if text: plain_part = MIMEText(text, 'plain', charset)
        if html: html_part = MIMEText(html, 'html', charset)

        is_alternative = html and text
        layers = []
        if attachments or is_alternative:
            msg = MIMEMultipart() #mixed
            msg.set_charset(charset)
            msg.preamble = 'This is a multi-part message in MIME format.'
            msg.epilogue = ''
            layers.append(msg)

            if is_alternative:
                msgAlternative = MIMEMultipart('alternative')
                msg.attach(msgAlternative)
                layers.append(msgAlternative)

            if text:
                layers[-1].attach(plain_part)
            if html:
                layers[-1].attach(html_part)

        elif text:
            msg = plain_part
        else: #html only
            msg = html_part

        for path in attachments:
            msg.attach(self.getAttachment(path, charset))

        msg['From'] = self.gmail_user
        msg['To'] = to
        msg['Subject'] = subject

        mailServer = smtplib.SMTP("smtp.gmail.com", 587)
        mailServer.ehlo()
        mailServer.starttls()
        mailServer.ehlo()
        mailServer.login(self.gmail_user, self.gmail_pwd)
        mailServer.sendmail(self.gmail_user, to, msg.as_string())
        # Should be mailServer.quit(), but that crashes...
        mailServer.close()

Algunos tests (ejemplos, casos de uso):

Archivo: GmailMail_tests.py

# -*- coding: utf-8 -*-

from GmailMail import GmailMail
from urllib2 import urlopen

text = u"""\
Éste es el contenido en modo texto plano
Tenemos acentos y eñes.

"""
url = "http://python.com.ar/moin"
html = urlopen(url).read()

user = 'XXXXXX@gmail.com' # mi usuario de GMail
pwd  = '********'         # mi contraseña de GMail

m = GmailMail(user, pwd)

print "mandando texto plano solamente"
m.send(user, u'prueba de sólo texto', text)

print "mandando html solamente"
m.send(user, u'prueba con sólo html', html=html)

print "mandando texto plano y html (sin attachments)"
m.send(user, u'prueba con texto plano y html (sin attachments)', text, html)

print "mandando texto plano y attachments"
m.send(user, u'prueba con texto plano y attachments', text, attachments=['GmailMail.py'])

print "mandando html y attachments"
m.send(user, u'prueba con html y attachments', html=html, attachments=['GmailMail.py'])

print "mandando attachments solamente"
m.send(user, u'prueba con attachments solamente', attachments=['GmailMail.py'])

print "mandando todo"
m.send(user, u'prueba con todo', text, html, attachments=['GmailMail.py'])