From the email:
We wanted to let you know that we added a new asset for trading - EOS tokens! The EOS platform is designed to scale the mainstream development of decentralized applications for large businesses, and claims to the first platform to do so. Check out our blog to learn more!
More info on the Kraken's blog.
Keep in mind that you can check out EosScan to keep track of the EOS price of all previous and future ICO windows. Make sure you don't pay to much on the exchanges!