This plugin is outdated and might not be supported anymore
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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

Details

Plugin code:
wp-smtp-config
Plugin version:
1.2.0
Outdated:
Yes
WP version:
3.0 or higher
PHP version:
or higher
Test up to WP version:
4.9.26
Total installations:
200
Last updated:
2018-11-12
Rating:
Times rated:
2
email
mail
phpmailer
smtp
ssl