Today, I setup mail() function for php. One of the Developer told me, can't send mail with mail() function. Are you enable in php.ini ? Oh! I think I need to setup mail() in our server. I reply like that. But I don't know how to enable it. I don't worry about that because our server is Ubuntu. I found following link and I setup and then it's OK. How nice ? Just take 30 minutes and problem has been solove. I love Ubuntu and opensource,too. https://help.ubuntu.com/community/Exim4 First we need to install exim4 look like that after that we need to config exim4 I made setup by step with wizard. It's easy. After that, I change php.ini in look like that. OK. Done. Restart the apache and it's working.