My custom suppor center problem with the code - not sending answer via email to the client

I have a custom CMS that I made but I have the following problem now. I'm making sth like support center on the ACP. I have a page Contacts(where clients/members) fill the form and in the ACP I have inbox(where I recieve their form entry). Now I'm trying to make in the ACP - ContactMail-Edit(which will help me to check their entry and I have in it 1 more form to answer.) I made the connection and the additional table rows like supportname and supportanswer. And this is what I tried. If you want you can contact me on discord(GyooDev#0143) and I can send you pics of the inbox and contact-answer page.

<?php
$getid = $_GET['id'];
if (!$_POST['supmailanswer'])
{
$our = mysqli_query($conn,"SELECT * FROM contact where id='$getid' ");
while($r=mysqli_fetch_array($our)){
?>
<div class="alert alert-info text-center" role="info"><i class="fas fa-inbox"></i> Contact form recieved on <?PHP echo"$r[date]"; ?>. Sender IP: <?PHP echo"$r[ip]"; ?></div>
<div class="input-group mb-3">
<span class="input-group-text">Name</span>
                <p class="form-control"><?PHP echo"$r[name]"; ?></p>
            </div>
                  <div class="input-group mb-3">
                     <div class="input-group-prepend">
                        <span class="input-group-text" id="inputGroup-sizing-default">Reason</span>
                     </div>
                     <p class="form-control"><?PHP echo"$r[reason]"; ?></p>
                  </div>
                  <div class="input-group mb-3">
                     <div class="input-group-prepend">
                        <span class="input-group-text" id="inputGroup-sizing-default">Email</span>
                     </div>
                     <p class="form-control"><?PHP echo"$r[email]"; ?></p>
                  </div>
                  <div class="input-group mb-3">
                     <div class="input-group-prepend">
                        <span class="input-group-text" id="inputGroup-sizing-default">Discord</span>
                     </div>
                     <p class="form-control"><?PHP echo"$r[discord]"; ?></p>
                  </div>
                  <div class="input-group mb-3">
                     <div class="input-group-prepend">
                        <span class="input-group-text" id="inputGroup-sizing-default">Message</span>
                     </div>
                     <p class="form-control"><?PHP echo"$r[message]"; ?></p>
                  </div>

                     </div></div>
</hr>
<form action="" method="post">
                  <div class="input-group mb-3">
                <span class="input-group-text">Support Name</span>
                <input type="text" class="form-control" name="supportname" required>
            </div>
            <div class="input-group mb-3">
                <span class="input-group-text">Support Answer</span>
                <input type="text" class="form-control" name="supportanswer" required>
            </div>
                  <input type="submit" name="supmailanswer" value="Answer" class="btn btn-primary" />
               </form>
               <?php 
            }
        }
        
            else{
            if(isset($_POST['supmailanswer'])){
                $clientmail= $_GET['email'];
                $supname = strip_tags(htmlspecialchars($_POST['supportname']));
                $supansw = strip_tags(htmlspecialchars($_POST['supportanswer']));
                $to = ".$clientmail.";
                $subject = "GKDev - Support reply to your Contact Form entry!";
                $body = "You have received a new message from your website contact form.\n\nHere are the details of the Support Answer:\n\nName: ".$supname."\n\nAnswer:\n ".$supansw."";
                $header = "From: myemail@mailcompany.com\n";
                $header .= "Reply-To: myemail@mailcompany.com"; 
                $header .= "Content-Type: text/html; charset=UTF-8\r\n";
                mail($to, $subject, $body, $header);
                }


            } 
                if (isset($_POST['supmailanswer'])) {
                    $support = trim(mysqli_real_escape_string($conn, htmlspecialchars($_POST['supportname'])));
                    $supportanswer = trim(mysqli_real_escape_string($conn, htmlspecialchars($_POST['supportanswer'])));
                    $status = 1;
                    if (empty($supportanswer)) {
                        echo "<div class='alert alert-danger' role='alert'>Please, provide your answer!</div>";
                    } else {
                        $update = mysqli_query($conn, "Update contact set supportname = '$support' , supportanswer = '$supportanswer' , status = '$status' where id = '$getid'");
                        echo "<div class='alert alert-success' role='alert'>Answered successfully!</div>";
                        echo "<meta http-equiv=Refresh content=2;url=inbox.php>";
                        mysqli_close($conn);
                    }
                  }
                             ?>