After submitting registration, allow user to resent confirmation email on his/her own request. The first automatic attempt to deliver may be unsuccessful for any reason.

Make unconfirmed registrations expire after certain amount of time, to free nick/email from database.

The resent functionality may be provided in few example scenarios:

1. after successful login with limited functionality and notifying user, that his account was not confirmad.

2. input, for entering email address used in registration.

3. any better idea