Ask HN: How to mine my inbox.

I use gmail and over the years have accumulated a lot of mails. Some that I'd like to keep and some that I'd like to get rid off. The Issue is that I have about 5000 emails and going one by one is not an option. I would like to know if there are any tools that will allow me to mine my inbox orif there is a better way to deal with the problem of having a big inbox, because if the size of the inbox keeps growing it just becomes "noise" and from that point forward having or not having that data(email) is the same.