# lib/email_validator.rb
class EmailValidator < ActiveModel::EachValidator

  def validate_each(object, attribute, value)
    unless value =~ /^([^@\s]+)@((?:[-a-z0-9]+\.)+[a-z]{2,})$/i
      object.errors[attribute] << (options[:message] || "is not valid") 
    end
  end

end