We used to wonder why everyones insisted we have a clause in our agreement to recognise that the data was owned by the client. Then we worked out that some other vendors kept control of the data as a means of locking their customers in.
With Campaign Master you can - at any time and without us even knowing about it - export any or all of your recipients and all the data we have about them.
Apart from the "it's my data" aspect, it also means that if you want, for example, to give the regional manager a file containing all the people in their region who clicked on the "special offer" link more than once, you can. That whole exercise would take less than 30 seconds.