500（内部服务器错误）angularjs php

Question

HTML code 
 <form>
                <div class="list">
                    <div class="list list-inset" >
                        <label class="item item-input"  id="descriptions">
                            <input type="text" height:"90" class="description" placeholder="Description ..." ng-model="data.describe" required>
                        </label>
                        <label input="email" class="item item-input" id="email" ng-model="data.email" required >
                            <span class="input-label">Email</span>
                            <input type="email">
                        </label>
                        <label class="item item-input" id="date">
                            <span class="input-label">Date</span>
                            <input type="date">
                        </label>     
                    </div>
                    <button class="button button-block button-balanced" type="submit" ng-click="AddItem(); submitForm()">
                        Add Item
                    </button>
                    <button class="button button-block button-assertive" ng-click="closeModal()"> cancel</button>

                </div>
            </form>
app.js
 $scope.submitForm = function() {
        console.log("posting data....");
        $http.post('localhost:80/api.php', JSON.stringify($scope.data)).success(function () {/*success callback*/ });
    };

PHP COde

<?php 

   $name=$_POST['descriptions']; 
    $email=$_POST['email']; 
    $message=$_POST['date'];
    var_dump($name);

    if (($descriptions =="")||($email=="")||($date=="")) 
        { 
        echo "All fields are required, please fill <a href=\"\">the form</a> again."; 
        } 
    else{         
        $from="From: $descriptions<$email>\r\nReturn-path: $email"; 
        $subject="Message sent using your contact form" + $date; 
        mail("testing@gmail.com", $subject, $message, $from); 
        echo "Email sent!"; 
        } 

?>

我正在尝试通过电子邮件将表单结果发送到输入字段但收到错误：500（内部服务器错误）。我确信我正在给出正确的端口号，我的wamp正在运行。我在Google Chrome上运行我的应用程序。