intermittent smtp module problems (with sendmail) in python 2.2.1

[Karl Ehr]

I have written the following simple program to monitor a single URL,
and notify me via email whenever this URL changes.    Intermittently,
I raise the following exception:

Traceback (most recent call last):
  File "./urlwatch.py", line 34, in ?
    server.sendmail(sourceAddress, emailAddress, message)
  File "/usr/lib/python2.2/smtplib.py", line 621, in sendmail
    if not (200 <= self.ehlo()[0] <= 299):
  File "/usr/lib/python2.2/smtplib.py", line 377, in ehlo
    (code,msg)=self.getreply()
  File "/usr/lib/python2.2/smtplib.py", line 328, in getreply
    raise SMTPServerDisconnected("Connection unexpectedly closed")
smtplib.SMTPServerDisconnected: Connection unexpectedly closed


This is a copy of my code:

----------------------------------------
#!/usr/bin/env python

import os, sys, string, urllib, time, smtplib, shutil, filecmp

## functions & classes
## vars

sleeptime = 900  # seconds to sleep between polls
urltoget = 'http://some.domain.com/foo'
server = smtplib.SMTP('localhost') # server to relay smtp through for
alarms
emailAddress = 'user at somedomain.com' #  address to send alerts to
sourceAddress = 'fromuser at somedomain.com' # required!   must have
foo at domain.com form
message = 'Your monitored URL has changed!'

## Main:

# establish baseline (old version)
urlfile = urllib.urlretrieve(urltoget, 'oldurlfile')
print "Sleeping", sleeptime, " seconds."
time.sleep(sleeptime)

while 1:
  try:
    urlfile = urllib.urlretrieve(urltoget, 'newurlfile')
  except:
    print "Could not retrieve url from internet"
    sys.exit(-1)
 
  if filecmp.cmp('oldurlfile','newurlfile',shallow=0):
    print "the url is still the same"  
  else:
    print "the url has changed!!!"
    server.set_debuglevel(1)
    server.sendmail(sourceAddress, emailAddress, message)
    server.quit()
    time.sleep(10)

  shutil.copyfile('newurlfile','oldurlfile')

  # sleep until next iteration
  print "Sleeping", sleeptime, " seconds."
  time.sleep(sleeptime)
  
#EOF 

------------------------------------

tia, 

Karl