bool validateEmail(String value) {
	Pattern pattern =
    	r'^(([^<>()[\]\\.,;:\s@\"]+(\.[^<>()[\]\\.,;:\s@\"]+)*)|(\".+\"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$';
    return RegExp(pattern).hasMatch(value);
}

if (!validateEmail(e-postadress)) {
    // Ogiltig e-postadress
} else {
    // giltig e-postadress
}