How to deal with unverified users in Drupal?
you should try the Logingtoboggon module. it has this feature


  
  Allow users to login using either their username OR their e-mail address.
  Allow users to login immediately.
  Provide a login form on Access Denied pages for non-logged-in (anonymous) users.
  The module provides two login block options: One uses JavaScript to display the form within the block immediately upon clicking "log
  in". The other brings the user to a separate page, but returns the
  user to their original page upon login.
  Customize the registration form with two e-mail fields to ensure accuracy.
  Optionally redirect the user to a specific page when using the 'immediate login' feature.
  Optionally redirect the user to a specific page upon validation of their e-mail address.
  Optionally display a user message indicating a successful login.
  Optionally combine both the login and registration form on one page.
  Optionally have unvalidated users purged from the system at a pre-defined interval (please read the CAVEATS section of INSTALL.txt
  for important information on configuring this feature!).
  Integrates with Rules module to do various tasks when a user validates via    email validation process (see
  http://drupal.org/node/880904 for an example)
  


I have put the feature you are looking for in bold.