I made changes in config.inc.php set smtp authentication properly and able to send mails to external domains successfully. But once user login to roundcube and try to send mail to external user they get SMTP Authentication (535) error.
I have two config files active config.inc.php defaults.inc.php
By changing config.inc.php i am able to send mail thru installer script, tried copying same settings to defaults.inc.php but no success please guide.
Settings should go in the config.inc.php the defaults.inc.php should never be changed since it is overwritten on upgrades.
Thanks , i have to move all ldap related config to config file.
By the way i solved my problem by changing config.inc.php
from
$config['smtp_user'] = '%u';
to
$config['smtp_user'] = ";
But strange thing is installer script can send mail successfully with %u but roundcube front-end user can not.