private boolean validateEmail(String mail) {
Pattern p = null;
if(TextUtils.isEmpty(mail))
return false;
if(p == null)
p = Pattern.compile("^[_a-zA-Z0-9]+(\\.[_a-zA-Z0-9]+)*@[a-zA-Z0-9_-]+(\\.[a-z0-9A-Z-_]+)+$");
Matcher m = p.matcher(mail);
return m.matches();
}