Mechanize not working for automating gmail login in Google Appengine

I have used mechanize and deployed an app on GAE and it works fine. But, for an app that I am making, I am trying to automate login to gmail through mechanize. It doesn't work in the development environment on local machine as well as after deploying on appengine.

I have been able to use the same script to run it on my server through mod_python using PSP.

I found a lot of solutions here, but none of them seem to work for me. Here is a snippet of my code:

<snip>
br = mechanize.Browser()
response = br.open("http://www.gmail.com")
loginForm = br.forms().next()
loginForm["Email"] = self.request.get('user')
loginForm["Passwd"] = self.request.get('password')
response = br.open(loginForm.click())
response2 = br.open("http://mail.google.com/mail/h/")
result = response2.read()
<snip>

When I look at the result, all I get is the login page when used with appengine. But with mod_python hosted on my own server, I get the page with the user's inbox.