# -*- coding: utf-8 -*-
import os
from subprocess import Popen, PIPE

import smtplib
from email import Encoders
from email.MIMEBase import MIMEBase
from email.MIMEMultipart import MIMEMultipart
from email.MIMEText import MIMEText
from email.Utils import formatdate

import time
import datetime

# Емайл для отправки отчетов
reportMail=( 'alice@mail.ru', 'bob@mail.ru' )

msg = MIMEMultipart()
msg["From"] = "Monitoring script"
msg["Subject"] = "Monitoring"
msg['Date']    = formatdate(localtime=True)

msg.add_header('From', 'Monitoring')
msg.add_header('Reply-To', 'Monitoring')
msg.add_header('X-Mailer', 'Python')
msg.add_header('Content-type', 'text/html charset=utf-8')

# Добавление текста сообщения
msg.attach(MIMEText("Это текст письма"))

# Перебор значений кортежа
for currentReportMail in reportMail:
 print "Почтовый ящик "+currentReportMail+"\n"
 msg["To"] = currentReportMail

print "А в конце "+msg["To"]+"\n"

Почтовый ящик alice@mail.ru
Почтовый ящик bob@mail.ru
А в конце alice@mail.ru

msg["To"]

>>> from email.mime.multipart import MIMEMultipart
>>> 
>>> m = MIMEMultipart()
>>> str(m)
'From nobody Fri May 15 18:21:46 2015\nContent-Type: multipart/mixed; boundary="===============1058888429=="\nMIME-Version: 1.0\n\n--===============1058888429==\n\n--===============1058888429==--'
>>> m['To'] = 'x@x'
>>> m['To'] = 'y@y'
>>> m['To']
'x@x'
>>> str(m)
'From nobody Fri May 15 18:21:46 2015\nContent-Type: multipart/mixed; boundary="===============1058888429=="\nMIME-Version: 1.0\nTo: x@x\nTo: y@y\n\n--===============1058888429==\n\n--===============1058888429==--'
>>> 
>>> del m['To']
>>> m['To'] = 'z@z'
>>> m['To']
'z@z'
>>>