Business social network LinkedIn remembers and shows all e-mail addresses of an individual member. In the course of years people send each other invitations, whereby they sometimes use a different e-mail address, while they do link these invitations to a certain profile. Thus LinkedIn can build up a database of different e-mail addresses for every individual. The user then can choose what should be the primary address for communication between the brand LinkedIn and the user. Very smart.All brands will soon do this. They don't just have one e-mail address of an individual consumer in their database, but also all associated e-mail addresses. So that if an e-mail address doesn't work any more, they can send a message to an alternative e-mail address. In these times, in which it is always harder to find new clients (or reach them using traditional channels), you have to give more attention to keeping existing customers. At this time, it is five times as expensive to get a new client as compared to keeping an existing client; this ratio will change for the worse in the years to come. This type of extensions of the database therefore will prove to be very profitable.