Hi All. The "Could not execute: /usr/sbin/sendmail" error appears when i try to send mail from webpage. I trying to change strings in configuration.php file from: public $mailer = 'sendmail'; public $sendmail = '/usr/sbin/sendmail'; to: public $mailer = 'postfix'; public $sendmail = '/usr/sbin/postfix'; or : public $mailer = 'sendmail.postfix'; public $sendmail = '/usr/sbin/sendmail.postfix'; but "Could not instantiate mail function." error appears. CentOS 5.6 ISPconfig 18.104.22.168 Joomla1.7 I'm confused... What can I do? Thanks.