Can't send mail with php
I've problem with my system. When a client want to send e-mail by php on my first, it doesn't work. So I don't know how can I must configure it to work with my postfix on my third server. Is there a way to send e-mail without used my mail server ?
Thank you in advance for your help
4 virtual machines with Debian Lenny updated on proxmox (openvz) with ISPConfig 18.104.22.168
ns1 : http(s), ftp(s), DNS Master, ISPConfig
sql : MySQL database users
mail : All mail system
ns2 : DNS Slave