使用Mailjet在PHP中发送电子邮件

Question

我是PHP的新手，并且正在做一个仅在本地主机上的小项目。我需要它来实际发送电子邮件，以便可以验证它是否正常运行。程序是如何工作的，管理员可以填写表格并向数据库中的用户发送电子邮件，该表格将发送到运行API发送的页面。我使用Mailjet的示例进行了尝试，它实际上已将电子邮件发送给指定的收件人，但是我需要从表单中传递收件人，主题和正文，并且不会发送我在做什么错了？

emailForm.php

    <div id = "mail-create" class="col-6 border" style="display: none;">
          <h3 class="text-primary text-center">Send mail</h3>
          <form method="post" action="sendEmail.php">
            <input type="hidden" name="admin" value="1">
            <?php include('errors.php'); ?>
            <div class="form-group">
              <label for="firstname">Choose user</label>
              <select name="userEmail" id="userEmail">
                <?php foreach ($users as $user): ?>
                  <option value="<?=$user['email'] ?>"><?=$user['username'] ?></option>
                <?php endforeach; ?>
              </select>
            </div>
            <div class="form-group" action="action.php">
              <label for="subject">Subject</label>
              <input type="text" class="form-control" name="subject" id="subject">
            </div>
            <div class="form-group">
              <label for="message">Message</label><br>
              <textarea name="message" id="message" cols="50" rows="8" placeholder="Write message body here"></textarea>
            </div>
            <button type="submit" name="sendMail" value="send" class="btn btn-primary mb-2" >Send mail</button>
          </form>
        </div>  

sendEmail.php

    <?php
     require 'vendor/autoload.php';
     use \Mailjet\Resources;
     if(isset($_POST[‘sendMail’]){
    //passed in my actual api keys
       $mj = new \Mailjet\Client('MJ_APIKEY_PUBLIC','MJ_APIKEY_PRIVATE',true,['version' => 'v3.1']);
       $body = [
         'Messages' => [
           [
             'From' => [
               'Email' => "email@email.com",
               'Name' => "name"
             ],
             'To' => [
               [
                 'Email' => $_POST['userEmail'],
                 'Name' => "name"
               ]
             ],
             'Subject' => $_POST['userEmail'],
             'TextPart' => "My first Mailjet email",
             'HTMLPart' =>$_POST['message'],
             'CustomID' => "AppGettingStartedTest"
           ]
         ]
       ];
       $response = $mj->post(Resources::$Email, ['body' => $body]);
       $response->success() && var_dump($response->getData());
     }
     ?>