Today I had to access a facebook account that I use for testing purposes. It had been a long time since I’d used it, so my first guess at the password was wrong. Facebook moved me to a page that explained how to retrieve a lost password along with a login form to try again, which is what I would expect any site to do in that situation. I tried with a different password that happened to be correct and logged in successfully.
Later, however, I noticed something that facebook had done just after my first attempt. They had sent an email to my sock puppet’s email account with a link to “login instantly” and reset my password.
I can guess that they’ve looked in to the behavior of the the “seldom” user and noticed that people that don’t log in regularly are likely to forget their passwords. Rather than hope they keep trying, facebook immediately sends an email to the user which acts as a simpler authentication and leads them to a painless method of restoring their access.
By anticipating and address the “seldom” user’s problems, they can encourage that user to get involved with their product and perhaps become an occasional or frequent user.