This plugin configures WordPress and WordPress MU to use a SMTP server when sending emails instead of the default PHP mail() function.
You will configure your SMTP settings in your wp-config.php file instead of the settings page.
The advantage is that no admin of your blog can read the settings.
And you only have to place your settings once in cases of a WordPress MU installation.
A sample configuration:
/**
* WordPress SMTP server
*/
define('WP_SMTP_HOST', 'mail.example.com');
define('WP_SMTP_PORT', 25); // obligatory - default: 25
define('WP_SMTP_ENCRYPTION', 'tls'); // obligatory ('tls' or 'ssl') - default: no encryption
define('WP_SMTP_USER', 'username'); // obligatory - default: no user
define('WP_SMTP_PASSWORD', 'password'); // obligatory - default: no password
define('WP_SMTP_FROM', 'John Doe <john.doe@example.com>'); // obligatory - default: no custom from address
define('WP_SMTP_REPLYTO', 'Jane Doe <jane.doe@example.com>'); // obligatory - default: no custom reply to address