Confirming website registrations

Confirming email addresses during a website registration process is a good practice. It stops people from creating fake accounts, abusing  resources and using that site as a mechanism for harassment. But simply sending out a confirmation mail is not sufficient to prevent problems, particularly when everything about the process assumes that unconfirmed registrations are actually valid and not problem accounts.
I’ve had a couple recent experiences with companies attempting to use email confirmation, but failing pretty miserably. In each case a website set up a process where a user could register an account on the site. Both sites required confirmation of the registration email addresses as part of the process. But in each case there were some major failures that result in non-customers getting email.
Tomorrow I’ll talk about those two specific cases. I’ll also provide specific suggestions on how not to fall into the same trap and actually send opt-in email.