Privacy, yes this is an issue. If you give out the names, you have to give them notice that you are giving out their names and give them the chance to opt out of such information sharing.
Charity event or no, how do you know the list of names and addresses aren't passed on to, say, another charitable organization that starts mailing promotions to your customers. You don't want to get this kind of thing started.
_________________________
Member of the National Sarcasm Society - like we need your support!