when the smtp server auth with 'username', the smtp.py client will thow exception

New submission from itfront <None>:

when I use the smtp.py to send email,I got exception:
Unhandled Error
Traceback (most recent call last):
  File "/usr/local/lib/python2.6/site-packages/Twisted-8.2.0-py2.6-linux-i686.egg/twisted/python/log.py", line 84, in callWithLogger
    return callWithContext({"system": lp}, func, *args, **kw)
  File "/usr/local/lib/python2.6/site-packages/Twisted-8.2.0-py2.6-linux-i686.egg/twisted/python/log.py", line 69, in callWithContext
    return context.call({ILogContext: newCtx}, func, *args, **kw)
  File "/usr/local/lib/python2.6/site-packages/Twisted-8.2.0-py2.6-linux-i686.egg/twisted/python/context.py", line 59, in callWithContext
    return self.currentContext().callWithContext(ctx, func, *args, **kw)
  File "/usr/local/lib/python2.6/site-packages/Twisted-8.2.0-py2.6-linux-i686.egg/twisted/python/context.py", line 37, in callWithContext
    return func(*args,**kw)
--- <exception caught here> ---
  File "/usr/local/lib/python2.6/site-packages/Twisted-8.2.0-py2.6-linux-i686.egg/twisted/internet/pollreactor.py", line 186, in _doReadOrWrite
    why = selectable.doRead()
  File "/usr/local/lib/python2.6/site-packages/Twisted-8.2.0-py2.6-linux-i686.egg/twisted/internet/tcp.py", line 463, in doRead
    return self.protocol.dataReceived(data)
  File "/usr/local/lib/python2.6/site-packages/Twisted-8.2.0-py2.6-linux-i686.egg/twisted/protocols/basic.py", line 231, in dataReceived
    why = self.lineReceived(line)
  File "/usr/local/lib/python2.6/site-packages/Twisted-8.2.0-py2.6-linux-i686.egg/twisted/mail/smtp.py", line 1052, in lineReceived
/13823106429
    return self.currentContext().callWithContext(ctx, func, *args, **kw)
  File "/usr/local/lib/python2.6/site-packages/Twisted-8.2.0-py2.6-linux-i686.egg/twisted/python/context.py", line 37, in callWithContext
    return func(*args,**kw)
--- <exception caught here> ---
  File "/usr/local/lib/python2.6/site-packages/Twisted-8.2.0-py2.6-linux-i686.egg/twisted/internet/pollreactor.py", line 186, in _doReadOrWrite
    why = selectable.doRead()
  File "/usr/local/lib/python2.6/site-packages/Twisted-8.2.0-py2.6-linux-i686.egg/twisted/internet/tcp.py", line 463, in doRead
    return self.protocol.dataReceived(data)
  File "/usr/local/lib/python2.6/site-packages/Twisted-8.2.0-py2.6-linux-i686.egg/twisted/protocols/basic.py", line 231, in dataReceived
    why = self.lineReceived(line)
  File "/usr/local/lib/python2.6/site-packages/Twisted-8.2.0-py2.6-linux-i686.egg/twisted/mail/smtp.py", line 1052, in lineReceived
    why = self._okresponse(self.code,'\n'.join(self.resp))
  File "/usr/local/lib/python2.6/site-packages/Twisted-8.2.0-py2.6-linux-i686.egg/twisted/mail/smtp.py", line 1372, in esmtpState_challenge
    self._authResponse(auth, resp)
  File "/usr/local/lib/python2.6/site-packages/Twisted-8.2.0-py2.6-linux-i686.egg/twisted/mail/smtp.py", line 1388, in _authResponse
    self.sendLine(encode_base64(resp, e

------------------------------------------------
finally , I find out that , at about line 1379:
def _authResponse(self, auth, challenge):
        self._failresponse = self.esmtpAUTHDeclined

        try:
            challenge = base64.decodestring(challenge)
            challenge = challenge.capitalize()  #add this!!

----------
Type     : defect
Component: core
Keywords : 
Priority : high
Nosy     : 
----------
http://twistedmatrix.com/trac/ticket/4055