python : send a mail (text), with attachments (See related posts)

I try the following before & success to send an e-mail using python.exe to compile the .py, but when I use py2exe to compile .py to .exe and run .exe some error exist, why??

error after run .exe:
<img="http://img.photobucket.com/albums/v200/bb1668/error.jpg"></img>

the following is my .py:

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

import os

def sendMail(to, fm, subject, text, files=[], server="192.168.0.99"):
text=str(text)
assert type(to)==list
assert type(files)==list
fro = fm

msg = MIMEMultipart()
msg['From'] = fro
msg['To'] = COMMASPACE.join(to)
msg['Date'] = formatdate(localtime=True)
msg['Subject'] = subject
msg.attach( MIMEText(text) )
for file in files:
part = MIMEBase('application', "octet-stream")
part.set_payload( open(file,"rb").read() )
Encoders.encode_base64(part)
part.add_header('Content-Disposition', 'attachment; filename="%s"'
% os.path.basename(file))
msg.attach(part)

smtp = smtplib.SMTP(server)
smtp.sendmail(fro, to, msg.as_string() )
smtp.close()