Many companies have a database of potential, existing or previous clients that they may call upon from time to time when they need to drum up some business. Car dealerships do this often as they will have details of when a car has new car has been sold and therefore often contact the customer when it is approaching three years old as many people change their car then as the this is when a new car needs to start having Mot’s etc.
This often works well for many car garages especially if the sales person that sold them the original car can then contact them again years down the line. People like to feel valued and if a salesperson remembers them and can talk about specific details of when they purchased their previous car, it is often enough to get the customer to come down to the show room.
With direct marketing you often get records that are out of date, so your marketing is only as good as your list is. This is why it is vital to try and keep it updated as much as possible.