CODE EXAMPLE FOR RUBY

rails validate email

validates_format_of :email, 
  :with => /^(|(([A-Za-z0-9]+_+)|([A-Za-z0-9]+-+)|([A-Za-z0-9]+.+)|([A-Za-z0-9]+++))*[A-Za-z0-9]+@((w+-+)|(w+.))*w{1,63}.[a-zA-Z]{2,6})$/i