WordPress: SMTP configuration

enable-html.php

<?php

/**
 * Set body as HTML.
 */
function set_html_content_type() 
{
    return 'text/html';
}

add_filter('wp_mail_content_type', 'set_html_content_type');

wp_mail('[email protected]', 'Subject', 'Message');

// Reset content-type to avoid conflicts -- https://core.trac.wordpress.org/ticket/23578
remove_filter('wp_mail_content_type', 'set_html_content_type');

smtp-conf.php

<?php

define('SMTP_DSN', 'smtp://user:pass@host:25?auth=1');

// Do not edit below this line.
add_action('phpmailer_init', function($phpmailer) {

    if (! defined('SMTP_DSN'))
        return;

    $smtp_data = parse_url(SMTP_DSN);
    parse_str($smtp_data['query'], $smtp_data_query);

    $phpmailer->isSMTP();
    $phpmailer->Host = $smtp_data['host'];
    $phpmailer->SMTPAuth = isset($smtp_data_query['auth'])? boolval($smtp_data_query['auth']) : false;
    $phpmailer->Port = $smtp_data['port'];
    $phpmailer->Username = $smtp_data['user'];
    $phpmailer->Password = $smtp_data['pass'];
});