PHP Mail Returning False But Still Sends I have a fresh install of ISPConfig 3 on CentOS 6.3, thanks to the awesome tutorial here http://www.howtoforge.com/perfect-server-centos-6.2-x86_64-with-apache2-ispconfig-3 I'm having some issues with PHP mail not behaving well. PHP mail() is returning false, however, the mail still is being sent successfully. This is an issue however because scripts need to know that mail was successful. I'm not sure why this is happening. The php script is very simple and just sends an email using the mail() function. I'm using mod_php for the site. Here is my /var/log/maillog after this happens which I am having trouble interpreting. Can anyone help me figure out what is going on here?