Q: @icloud.com email not working

Hi, I have been a long time user of apple email since .mac and i am able to receive email sent to my @mac.com or @me.com email address. In the advanced email settings in iOS 6, there is an option to send email from my @icloud.com address as well as @mac.com and @me.com. The problem is that my @icloud.com  address doesn't appear to work, if i send mail to it, it gets rejected by the server that says that email address does not exist.