Email List Cleanup

Before I start, I know this is a dumb question but I thought I'd just check before I put a LOAD of work in.

I have acquired a list of 8 million email addresses which I suspect to be pretty dirty with a fairly high bounce rate.

Does anyone here know of an easy way to cleanup the list short of sending a mailout and filtering out the bounces?

Many thanks
Matt

Yeah, you can get tons of data if you want to spend a bunch of money. RapLeaf is fucken awesome. Have a look: http://www.rapleaf.com/