If you want to validate email then use input with type="email" instead of type="text". AngularJS has email validation out of the box, so no need to use ng-pattern for this.
Here is the example from original documentation:
<script>
function Ctrl($scope) {
$scope.text = '[email protected]';
}
</script>
<form name="myForm" ng-controller="Ctrl">
Email: <input type="email" name="input" ng-model="text" required>
<br/>
<span class="error" ng-show="myForm.input.$error.required">
Required!</span>
<span class="error" ng-show="myForm.input.$error.email">
Not valid email!</span>
<br>
<tt>text = {{text}}</tt><br/>
<tt>myForm.input.$valid = {{myForm.input.$valid}}</tt><br/>
<tt>myForm.input.$error = {{myForm.input.$error}}</tt><br/>
<tt>myForm.$valid = {{myForm.$valid}}</tt><br/>
<tt>myForm.$error.required = {{!!myForm.$error.required}}</tt><br/>
<tt>myForm.$error.email = {{!!myForm.$error.email}}</tt><br/>
</form>
For more details read this doc: https://docs.angularjs.org/api/ng/input/input%5Bemail%5D
Live example: http://plnkr.co/edit/T2X02OhKSLBHskdS2uIM?p=info
UPD:
If you are not satisfied with built-in email validator and you want to use your custom RegExp pattern validation then ng-pattern directive can be applied and according to the documentation the error message can be displayed like this:
The validator sets the pattern error key if the ngModel.$viewValue does not match a RegExp
<script>
function Ctrl($scope) {
$scope.text = '[email protected]';
$scope.emailFormat = /^[a-z]+[a-z0-9._]+@[a-z]+\.[a-z.]{2,5}$/;
}
</script>
<form name="myForm" ng-controller="Ctrl">
Email: <input type="email" name="input" ng-model="text" ng-pattern="emailFormat" required>
<br/><br/>
<span class="error" ng-show="myForm.input.$error.required">
Required!
</span><br/>
<span class="error" ng-show="myForm.input.$error.pattern">
Not valid email!
</span>
<br><br>
<tt>text = {{text}}</tt><br/>
<tt>myForm.input.$valid = {{myForm.input.$valid}}</tt><br/>
<tt>myForm.input.$error = {{myForm.input.$error}}</tt><br/>
<tt>myForm.$valid = {{myForm.$valid}}</tt><br/>
<tt>myForm.$error.required = {{!!myForm.$error.required}}</tt><br/>
<tt>myForm.$error.pattern = {{!!myForm.$error.pattern}}</tt><br/>
</form>
Plunker: https://plnkr.co/edit/e4imaxX6rTF6jfWbp7mQ?p=preview