JavaScript email validation

JavaScript regular email validation:
 function validateRegularEmail(email) {
  var regex = /^([a-zA-Z0-9_.+-])+\@(([a-zA-Z0-9-])+\.)+([a-zA-Z0-9]{2,4})+$/;
  return regex.test(email);
}
JavaScript gmail validation:
 function validateGmail(email) {
    //Gmail required: %@gamil.com
    var re = /^\s*[\w\-\+_]+(\.[\w\-\+_]+)*\@[\w\-\+_]+\.[\w\-\+_]+(\.[\w\-\+_]+)*\s*$/;
    if (re.test(email)) {
        if (email.indexOf('@gmail.com', email.length - '@gmail.com'.length) !== -1) {
            return true;
        } else {
            bootbox.alert('Please enter Gmailaddress.');
        }
    } else {
        bootbox.alert('Please enter Gmail  address.');
    }
}

To use this function:
testmail ='test@htomail.com';
if(!validateRegularEmail(testmail)) alert('Wrong email adress');