s = smtplib.SMTP('smtp.uk.xensource.com')
s.set_debuglevel(1)
msg = MIMEText('body')
sender = 'me@example.com'
recipients = ['john.doe@example.com', 'john.smith@example.co.uk']
msg['Subject'] = 'subject line'
msg['From'] = sender
msg['To'] = ', '.join(recipients)
s.sendmail(sender, recipients, msg.as_string())
How to send email to multiple recipients using python smtplib?