Fastest e-mail client?

Hello,

Do you guys know of any good, fast, gui e-mail client. I am using Sylpheed, but it hangs a bit and whenever there is a period(lastname.firstname@whatever.com) it errors out. I need support for IMAPs and POP3s, too.

No Mozilla or KMail; they are kind of slow for me. I have a old laptop with 64MB ram and 166/266 Pentium II running RH7.1

Regards,
Sundar