import smtplib

auth_user = 'postmaster@a.cn'
auth_pass = 'www'
to = ['test@a.cn']

msg = """From: <forge@domain.com>
To: <me@gmail.com>
Date: Tue, 28 Jun 2016 01:32:54 +0800
Subject: Test

Test mail body.
"""

s = smtplib.SMTP('127.0.0.1', 587)
s.ehlo('test.com')
s.starttls()
s.ehlo('test.com')

try:
    s.login(auth_user, auth_pass)

    # Mail will be sent out.
    s.sendmail(auth_user, ','.join(to), msg)

    # Mail will be rejected due to sender login mismatch.
    #s.sendmail('forge@domain.com', ','.join(to), msg)
except Exception, e:
    print e
finally:
    s.quit()