Alternatively, you could email every address the bank leaked to you and tell them:
- The bank leaked their email addresses
- How using Bitcoins will allow them to remain anonymous and not rely on a 3rd party
- Links to more info about Bitcoin
Simply notifying the recipients would not be commercial so it wouldn't violate U.S. anti-spam (Unsolicited Commercial E-mail) laws. I don't know the laws in that jursidiction. Adding Bitcoin could cause it to be interpreted as being a commercial message.
Regardless that's more like a boiler room type / telemarketer tactic. The message about Bitcoin as a pseudonymous store of value will reach them eventually, it is probably is best not to give a bad first impression.