diff --git a/agent/ajax.php b/agent/ajax.php
index 3d8331ae..eec7bdd2 100644
--- a/agent/ajax.php
+++ b/agent/ajax.php
@@ -700,6 +700,34 @@ if (isset($_GET['client_duplicate_check'])) {
     echo json_encode($response);
 }
 
+if (isset($_GET['contact_email_check'])) {
+    enforceUserPermission('module_client', 2);
+
+    $email = sanitizeInput($_GET['email']);
+    $domain = sanitizeInput(substr($_GET['email'], strpos($_GET['email'], '@') + 1));
+
+    $response['message'] = ""; // default
+
+    if (strlen($email) >= 3) {
+
+        // 1. Duplicate check
+        $sql_contacts = mysqli_query($mysqli, "SELECT contact_email FROM contacts WHERE contact_email = '$email' LIMIT 1");
+        if (mysqli_num_rows($sql_contacts) > 0) {
+            while ($row = mysqli_fetch_array($sql_contacts)) {
+                $response['message'] = "<i class='fas fa-fw fa-copy mr-2'></i> Potential duplicate: <i>" . nullable_htmlentities($row['contact_email']) . "</i> already exists.";
+            }
+        }
+
+        // 2. MX record check
+        if (!checkdnsrr($domain, 'MX')) {
+            $response['message'] = "<i class='fas fa-fw fa-exclamation-triangle mr-2'></i> E-mail domain invalid.";
+        }
+
+    }
+
+    echo json_encode($response);
+}
+
 if (isset($_GET['ai_reword'])) {
 
     header('Content-Type: application/json');
diff --git a/agent/modals/contact/contact_add.php b/agent/modals/contact/contact_add.php
index 69db0a7e..9e5df3ba 100644
--- a/agent/modals/contact/contact_add.php
+++ b/agent/modals/contact/contact_add.php
@@ -148,7 +148,10 @@ ob_start();
                         <div class="input-group-prepend">
                             <span class="input-group-text"><i class="fa fa-fw fa-envelope"></i></span>
                         </div>
-                        <input type="email" class="form-control" name="email" placeholder="Email Address" maxlength="200">
+                        <input type="email" class="form-control" name="email" id="contact_email" placeholder="Email Address" maxlength="200" onfocusout="contact_email_check()">
+                    </div>
+                    <div class="mt-2">
+                        <span class="text-info" id="contact_check_info"></span>
                     </div>
                 </div>
 
@@ -339,6 +342,23 @@ $(document).ready(function() {
 });
 </script>
 
+<script>
+    // Checks contact emails
+    function contact_email_check() {
+        var email = document.getElementById("contact_email").value;
+        //Send a GET request to ajax.php as ajax.php?contact_email_check=true&email=email
+        jQuery.get(
+            "ajax.php",
+            {contact_email_check: 'email', email: email},
+            function(data) {
+                //If we get a response from ajax.php, parse it as JSON
+                const contact_check_data = JSON.parse(data);
+                document.getElementById("contact_check_info").innerHTML = contact_check_data.message;
+            }
+        );
+    }
+</script>
+
 <?php
 
 require_once '../../../includes/modal_footer.php';