Absolutely. I'm the lead developer - I spent almost 6 years working on anti-virus and anti-spam, so rest assured we know this is a big deal. :-) There is alot of quality stuff in the open source world already which we will be able to build on.
Update: To clarify why we left it out of the pitch - we just took it for granted that you can't have a functional e-mail client without dealing with spam.
Nothing I tried ever handled spam as well as Gmail, I was drowning in it, it's the number one reason I use Gmail. I see so little spam now I think if everyone used Gmail the spammers would have to give up.
There are plenty of nice-enough webmail UIs around, and people complain about the speed of Gmail but I find it perfectly fine. Spam's the thing.
Update: To clarify why we left it out of the pitch - we just took it for granted that you can't have a functional e-mail client without dealing with spam.