Andrew, Thanks for the feedback. BTW, I am new to twisted but not to python.

Anyway, there's nothing Twisted specific here that I can see.

I disagree -- I was trying to make a suggestion that would make future releases of twisted more bulletproof. Specifically, perhaps _parse() should be changed as follows (4 out of the last 5 lines are different): def _parse(url, defaultPort=None): parsed = urlparse.urlparse(url) scheme = parsed[0] path = urlparse.urlunparse(('','')+parsed[2:]) if defaultPort is None: if scheme == 'https': defaultPort = 443 else: defaultPort = 80 host, port = parsed[1], defaultPort if ':' in host: host, port = host.split(':') try: port = int(port) except ValueError: port = defaultPort return scheme, host, port, path But I will not change the copy of client.py on my computer. I worked around this problem by making sure all the URL's were clean before giving them to twisted. Going at this from the top down (or bottom up, depending on your perspective): lURLs = map( GetCleanURL, lURLs ) def GetCleanURL( sURL ): # return UrlUnSplitMore( UrlSplitMore( sURL ) ) UrlUnSplitMore and UrlSplitMore have longer lines which this mail client would wrap, and the result would look terrible. In case you are interested, they are in this plain text file: http://www.advanced-app.com.hk/MiscJunk/UrlSplitAndUnSplit.txt Maybe I am making a suggestion to change twisted in the wrong place. I will try posting my suggested change as a "bug" -- client.py crashes on a URL that most browsers clean up automatically with no problem. Thanks, Rick