If you have more than one email address, and you've lost track of which one is subscribed to a netbeans.org mailing list, you should be able to find out by looking at the headers of a list message.
In your mail client, look for the "Return-path:" header. If you don't see it, you probably need to tell your client to display all headers. How to do this varies between clients - in Mozilla for eg, open the message, under the View menu choose Headers and select All. You should now see a lot of extra header info - towards the top should be one that looks something like (for example):
Return-path: <nbusers-return-49530-jsmith=hotmail.com@netbeans.org>
nbusers-unsubscribe-jsmith=hotmail.com@netbeans.org