E-mail Client

Hi.

I have a lot of e-mail accounts that I maintain for various web sites plus various personal ones.

I'm looking for a free e-mail client that is well set up. I use thunderbird now and as much as I like it I'm getting lost in my various e-mail accounts. I need something that can and will be better organized.

Do any of you have good suggestions for an e-mail client?

Thank you very much.