In Drupal 6 and 7, user using the password recovery, or "verify your email" registration process, will receive a mail with a one time login link.
Cliking the link will bring them to a one time login form they have to submit.
So here is a trick from sivaji from drupalgardens to bypass the one time login form.
On the mail template, found in drupal 7 on the account admin page ( admin/config/people/accounts ) add after [user:one-time-login-url] token "/login" so you have "[user:one-time-login-url]/login".
For Drupal 6 it will be "!login_url/login"
This will just do the trick !