multiple email textarea validation

<!DOCTYPE html>
<html>

  <head>
    <script data-require="underscore.js@*" data-semver="1.8.3" src="//cdnjs.cloudflare.com/ajax/libs/underscore.js/1.8.3/underscore-min.js"></script>
    <script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.2.26/angular.min.js"></script>
    <link href="style.css" rel="stylesheet" />
    <script src="script.js"></script>
  </head>

  <body ng-app="myApp">
    <div ng-controller="myCtrl">
      multiple emails:
            <form role="form" ng-submit="onSubmit()" novalidate="" name="shareSelectionForm">
        <div ng-class="{'has-error': shareSelectionForm.recipientEmail.$invalid}">
          <textarea type="text" class="form-control" multiple-emails="" required="" name="recipientEmail" ng-model="shareSelectionFormFields.recipientEmail"></textarea>
        </div>
      </form>
    </div>
  </body>

</html>

var app = angular.module("myApp", []);

app.controller('myCtrl', ['$scope', function($scope){

}])
    .directive('multipleEmails', function () {
      return {
        require: 'ngModel',
        link: function(scope, element, attrs, ctrl) {
          ctrl.$parsers.unshift(function(viewValue) {
  
            var regExp = new RegExp('[,\\s]+');
            var emails = _.compact(_.unique(viewValue.split(regExp)));
            // define single email validator here
            var re = /\S+@\S+\.\S+/; 
              
            // angular.foreach(emails, function() {
              var validityArr = emails.map(function(str){
                  return re.test(str.trim());
              }); // sample return is [true, true, true, false, false, false]
              console.log(emails, validityArr); 
              var atLeastOneInvalid = false;
              angular.forEach(validityArr, function(value) {
                if(value === false)
                  atLeastOneInvalid = true; 
              }); 
              if(!atLeastOneInvalid) { 
                // ^ all I need is to call the angular email checker here, I think.
                ctrl.$setValidity('multipleEmails', true);
                return viewValue;
              } else {
                ctrl.$setValidity('multipleEmails', false);
                return undefined;
              }
            // })
          });
        }
      };
    });

/* Styles go here */
.has-error textarea {
  background: red;
}