What are the potential risks or pitfalls of using PHP to authenticate with an SMTP server for mail sending?

One potential risk of using PHP to authenticate with an SMTP server for mail sending is that sensitive login credentials may be exposed if the code is not properly secured. To mitigate this risk, it is important to store credentials securely, such as in environment variables or a configuration file that is not publicly accessible. 

// Store SMTP credentials in a separate configuration file
$config = include 'config.php';

// Use the stored credentials to authenticate with the SMTP server
$transport = (new Swift_SmtpTransport($config['host'], $config['port'], $config['encryption']))
  ->setUsername($config['username'])
  ->setPassword($config['password']);

Keywords

PHP SMTP server authentication mail sending security vulnerabilities

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