System.out.println("E-Mail Adressen: " + emailAdressen("muster@muster.de"));

public static boolean emailAdressen(String emailAdressen) {
        Pattern pattern = Pattern.compile("^[A-Z0-9_!#$%&'*+/=?`{|}~^-]+(?:\\.[A-Z0-9_!#$%&'*+/=?`{|}~^-]+↵\n" +
                ")*@[A-Z0-9-]+(?:\\.[A-Z0-9-]+)*$", Pattern.CASE_INSENSITIVE);
        Matcher matcher = pattern.matcher(emailAdressen);
        return matcher.find();
    }