Unsubscribe and Blacklist

Even though you are not sending emails yourself (it's done by the server script from that contact form), you still might want to use the following PHP-script on your website to collect domains of sites where you have sent a message but who are not interested. This would prevent any further problems and not send there again. Instructions are also in the script for further details.

<?php

/*

  1. Upload this file to your webserver and call it e.g. unsubscribe.php
  2. In GSA Website Contact -> Edit Project ->Submission Content->Message add something like...

    Click the following link to unsubscribe: http://www.mywebsite.com/unsubscribe.php?d=%domain%
    
  3. in GSA Website Contact -> Options -> Global Filter -> add the URL to your $blacklist_filename from below
  
     http://www.mywebsite.com/blacklist.txt

*/

    $url_parameter_for_domain="d"; 
    $blacklist_filename="blacklist.txt";  //the filename where it is stored and where the program can access it to read unsubscribed data
    
    //a message given to the user
    $message_title="Successfully unsubscribed"; 
    $message_body="We apologize for any inconvenience. We will no longer contact you in the future.";
    $message_redirect_url=""; //if set, it will go to this URL after a short time
    
//------------------ the code starts below -------------

    //get domain and validate
    $domain=$_GET[$url_parameter_for_domain];    
    if(($domain!="") && (preg_match('/^(?:[-A-Za-z0-9]+\.)+[A-Za-z]{2,6}$/',$domain))) {
      file_put_contents($blacklist_filename, $domain."\n",FILE_APPEND);
    }
    
    //output some message
    echo "<html>\n".
         "  <head>\n".
         "    <title>".$message_title."</title>\n".
         '    <meta charset="utf-8">'."\n".
         '    <meta name="viewport" content="width=device-width,initial-scale=1">'."\n".    
         "    <style>\n".
         "      *{margin:0; padding:0; box-sizing:border-box;--textcolor:#fff;  --bgcolor:#121212;  --highlight:#2749c9;}\n".
         "      @media (prefers-color-scheme:dark){*{--textcolor:#141414;    --bgcolor:#f0f0f0;    --highlight:#ff7f00;}}\n".
         "      body{font-size:18px;  font-family:system-ui,sans-serif;  line-height:1.4;  color:var(--textcolor);  background:var(--bgcolor);  position:relative;  max-width:64em; margin:0 auto;}\n".
         "      header{padding:5vw 5vw 0 5vw; display:flex; flex-wrap:wrap; position:absolute; width:100%; z-index:2;}\n".
         "      header h1{font-size:1em;  flex:1;white-space:nowrap; padding:0 5vw .5em 0;}\n".
         "      p,ul,ol,article{max-width:60ch;margin-bottom:.6em;}\n".
         "    </style>\n";

    if($message_redirect_url!="") echo '    <meta http-equiv="refresh" content="5;url='.$message_redirect_url.'" />'."\n";
    
    echo "  </head>\n".
         "  <body>\n".
         "    <br><br><h1>".$message_title."</h1>\n".
         "    <br><p>".$message_body."</p>\n".
         "  </body>\n".
         "</html>";
         
?>