I'm trying to use domaikeys, and auth for rouncube.
$rcmail_config['smtp_server'] = '%h';
// SMTP port (default is 25; use 587 for STARTTLS or 465 for the
// deprecated SSL over SMTP (aka SMTPS))
$rcmail_config['smtp_port'] = 25;
// SMTP username (if required) if you use %u as the username Roundcube
// will use the current username for login
$rcmail_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
$rcmail_config['smtp_pass'] = '%p';
Error:
SMTP Error (535): Authentication failed.