Set smtp options in sample config as they are required now

config/config.inc.php.sample

@@ -41,7 +41,6 @@ $config['default_host'] = 'localhost';
 
 // SMTP server host (for sending mails).
 // To use SSL/TLS connection, enter hostname with prefix ssl:// or tls://
-// If left blank, the PHP mail() function is used
 // Supported replacement variables:
 // %h - user's IMAP hostname
 // %n - hostname ($_SERVER['SERVER_NAME'])
@@ -49,7 +48,7 @@ $config['default_host'] = 'localhost';
 // %d - domain (http hostname $_SERVER['HTTP_HOST'] without the first part)
 // %z - IMAP domain (IMAP hostname without the first part)
 // For example %n = mail.domain.tld, %t = domain.tld
-$config['smtp_server'] = '';
+$config['smtp_server'] = 'localhost';
 
 // SMTP port (default is 25; use 587 for STARTTLS or 465 for the
 // deprecated SSL over SMTP (aka SMTPS))
@@ -57,11 +56,11 @@ $config['smtp_port'] = 25;
 
 // SMTP username (if required) if you use %u as the username Roundcube
 // will use the current username for login
-$config['smtp_user'] = '';
+$config['smtp_user'] = '%u';
 
 // SMTP password (if required) if you use %p as the password Roundcube
 // will use the current user's password for login
-$config['smtp_pass'] = '';
+$config['smtp_pass'] = '%p';
 
 // provide an URL where a user can get support for this Roundcube installation
 // PLEASE DO NOT LINK TO THE ROUNDCUBE.NET WEBSITE HERE!