t-r.de/content/php/settings.php

<?php
// import PHPMailer classes into the global namespace
use PHPMailer\PHPMailer\PHPMailer;
use PHPMailer\PHPMailer\SMTP;
use PHPMailer\PHPMailer\Exception;

$dname = dirname(__FILE__); 
require $dname . '/../Exception.php';
require $dname . '/../PHPMailer.php';
require $dname . '/../SMTP.php';

// general constants
$general = [
  // site domain (used for building confirmation links)
/*  'domain' => 'tobias-radloff.de', */
  'domain' => 'localhost',
  // string concatenated with email address to create a non-recreatable md5 hash 
  'uniqueKey' => '***REMOVED***', // works like password salt  
  // file name of confirm script
  'confirmScript' => '/newsletter/confirm.php',
  // status code to be used when redirection to success or error page 
  'statusCode' => 'HTTP/1.1 303 See Other',
  // array of SQL statements used
  'sql' => [
    'create_table' => 'CREATE TABLE IF NOT EXISTS subscribers (id INTEGER PRIMARY KEY, email TEXT NOT NULL UNIQUE, name TEXT);',
    'create_record' => 'INSERT INTO subscribers(email, name) VALUES(:e, :n);',
    'read_record' => 'SELECT 1 FROM subscribers WHERE email = :e;',
    'update_record' => '',
    'delete_record' => 'DELETE FROM subscribers WHERE email = :e;'
  ]
]; 
// complete site URL
$general['siteURL'] = 'https://' . $general['domain']; 

// SMTP server information
$smtp = [
  'host' => '***REMOVED***
  'port' => 587,
  'username' => 'tobias',
  'password' => '***REMOVED***',
  'auth' => TRUE,
  'fromAddress' => '***REMOVED***',  //  'newsletter@tobias-radloff.de'
  'fromName' => 'Tobias Radloffs Newsletter',
];

// body of confirmation email
$bodyConfirmation = [
  'Hallo!',
  'Bitte bestätige die Anmeldung für meinen Newsletter, indem du auf den folgenden Link klickst:',
  '%Placeholder%', 
  'Bis bald und viele Grüße, Tobias' 
];

// contents of confirmation email
$mailConfirmation = [
  'subject' => 'Newsletter-Anmeldung bestaetigen',
  'bodyHTML' => '<p>' . implode('</p><p>', $bodyConfirmation) . '</p>',
  'bodyText' => implode("\n\n", $bodyConfirmation)
];

// database information
$db = [
  'sqlite' => [
    'dsn' => 'sqlite:../../newsletter.sqlite',
  ],
  'mysql' => [
    'dsn' => '',
    'host' => '',
    'port' => '',
    'username' => '',
    'password' => ''
  ]
];

function GetConfirmationHash($confEmail) {
  global $general;
  return md5($confEmail . $general['uniqueKey']);
}

// connects to database and returns PDO object
function getPDO($dbType = 'sqlite') {
  global $db;
  return new \PDO($db[$dbType]['dsn']);
}

// Sends an email to single recipient with subject and body specified in an array
function SendEmail($recipientAddress, $mailContents, $link = NULL) {
  global $general, $smtp;
  $mail = new PHPMailer(true);

  //Server settings
  //    $mail->SMTPDebug = SMTP::DEBUG_SERVER;                      //Enable verbose debug output
  $mail->isSMTP();
  $mail->Host       = $smtp["host"];
  $mail->SMTPAuth   = $smtp["auth"];
  $mail->Username   = $smtp["username"];
  $mail->Password   = $smtp["password"];
  //$mail->SMTPSecure = PHPMailer::ENCRYPTION_SMTPS;            //Enable implicit TLS encryption
  $mail->Port       = $smtp["port"];   //TCP port to connect to; use 587 if you have set `SMTPSecure = PHPMailer::ENCRYPTION_STARTTLS`

  //Recipients
  $mail->setFrom($smtp["fromAddress"], $smtp["fromName"]);
  $mail->addAddress($recipientAddress);     //Add a recipient

  //Content
  if (isset($link)) {
    $mailContents["bodyHTML"] = str_replace("%Placeholder%", $link, $mailContents["bodyHTML"]);
    $mailContents["bodyText"] = str_replace("%Placeholder%", $link, $mailContents["bodyText"]);
  }
  $mail->CharSet = "UTF-8";
  $mail->isHTML(true);
  $mail->Subject = $mailContents["subject"];
  $mail->Body    = $mailContents["bodyHTML"];
  $mail->AltBody = $mailContents["bodyText"];

  $mail->send();
}


function MakeSureTableExists($pdo) {
  global $general;
  $query = $pdo->prepare($general['sql']['create_table']);
  if ( ! $query->execute() ) {
//    error_log('Unbekannter Datenbankfehler beim Prüfen/Erzeugen der Tabelle.');
    return "Unbekannter Datenbankfehler";
  }
  return TRUE;
}

// returns true if record does not yet exist in database; error string otherwise
function NotAlreadySubscribed($email, $pdo = NULL) {
  if (!isset($pdo)) {
    $pdo = getPDO();
  }

  $result = MakeSureTableExists($pdo);
  if ( gettype($result) == "string" ) {
//    error_log("Datenbankfehler beim Adresscheck: {$result}");
    return $result; 
  }

  global $general;
  $query = $pdo->prepare($general['sql']['read_record']);
  if ( ! $query->execute([':e' => $email]) ) {
//    error_log("Datenbankfehler: Adresscheck für Emailadresse {$email} ergab einen Fehler.");       
    return "Fehler beim Zugriff auf Datenbank";
  }

  if ( $query->fetch() ) {
//    error_log("Adresscheck: Emailadresse {$email} ist bereits eingetragen.");
    return "Emailadresse {$email} ist bereits eingetragen";
  }

  // success
  return TRUE;
}

// redirects to specified URL via GET request and conveys an optional message; then exits  
function GracefulExit($location, $message = NULL) {
  global $general;
  header($general['statusCode']);
  if (isset($message)) {
    $location .= "?" . http_build_query(['msg' => $message]);
    error_log($location);
  }
  header("Location: {$location}");
  exit;
}
?>