[flexcoders] custom validate email with tooltip

[yonghan79]

Hi all,does anyone ever before create custom validators for emails?For example 
i'm typing my email,when i don't type the @ then the tooltip will show up and 
display you are missing the @,when i don't type the .com,the tooltip will 
display you are missing the domain...Do anyone mind to point me how to do 
it?Thanks a lot..