You have to set 'name' attribute to your input email :
<input type="email" name="email" data-ng-model="email" placeholder="Email" required />
For each field of your form, angularjs will set a value like: loginform[name-attribute].
For your information, your span will be visible only when required error is triggered (when your email is not empty, your span will be hidden).
[EDIT] See this fiddle: http://jsfiddle.net/k82at