Devise email validation regexp

config.email_regexp = /\A(([\p{L}0-9]+_+)|([\p{L}0-9]+\-+)|([\p{L}0-9]+\.+)|([\p{L}0-9]+\++))*[\p{L}0-9]+@(([\p{L}0-9]+\-+)|([\p{L}0-9]+\.))*[\p{L}0-9]{1,63}\.[\p{L}]{2,6}\z/i