From 42b9b3a62eeca1e600e5a8a71490c80177df88ed Mon Sep 17 00:00:00 2001
From: Brain <bus-20190613-chg@abrain.de>
Date: Wed, 24 Aug 2022 14:35:01 +0200
Subject: [PATCH] Set the return path via the envelope sender

---
 assets/php/contact_form.php | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/assets/php/contact_form.php b/assets/php/contact_form.php
index 9b2c73c..d6b93a6 100644
--- a/assets/php/contact_form.php
+++ b/assets/php/contact_form.php
@@ -34,17 +34,25 @@ function prepare_message_body(string $message, string $name) {
  *  phpmailer: Bibliothek, der per Composer installiert wird. Tut ganz gut mit SMTP.
  */
 function send_message_to_office(string $subject, string $message, string $name, string $email) {
+    $returnPath = filter_var(getenv('WTF_RETURN_PATH'), FILTER_VALIDATE_EMAIL);
+    $to = filter_var(getenv('WTF_CONTACT_TO'), FILTER_VALIDATE_EMAIL);
+
+    if (!$returnPath || !$to) {
+        error_log('Address for "To" or "Return-Path" is invalid');
+        return false;
+    }
+
     return mail(
-        getenv('WTF_CONTACT_TO'),
+        $to,
         "=?UTF-8?B?" . base64_encode($subject) . "?=",
         prepare_message_body($message, $name),
-        $additional_headers = array(
+        array(
             "From" => getenv('WTF_CONTACT_FROM'),
             "Reply-To" => $email,
-            "Return-Path" => getenv('WTF_RETURN_PATH'),
             "Content-Type" => "text/plain; charset=utf-8",
             "Content-Transfer-Encoding" => "base64",
         ),
+        "-f $returnPath"
     );
 }