$mail = new Mail();
$mail->setFrom('foo@example.com');
$mail->setTo('bar@example.com');
$mail->getHeaders()->set('Subject', 'Hello World');
$mail->setBody('Hello World');

$transport = new SendmailTransport();
$transport->sendMail($mail);

$transport = new CurlTransport('smtp.example.com');

// Zugangsdaten für den SMTP-Server
$credentials = new BasicCredentials();
$credentials->setUserName('foo');
$credentials->setPassword('bar');
$transport->setCredentials($credentials);

$transport->sendMail($mail);