I have a long-time customer who has an account on our web site. Some time back he placed an order that he wanted shipped to a friend. So he entered that information in the ship-to section.
Today, he returned to the site to place an order to be shipped to himself, only to find he could not log in. The site said that his email address didn't exist on our site. Apparently, when he entered the friend's details, he also entered their email address.
So today he ended up placing the order as a guest.
I went into his account and changed the shipping address back to his home address, and entered his email address in the email address field.
So all is well for now, but how can he avoid this in the future? How can he place an order and have it shipped to a friend without those details hijacking his account?