thehenrys.net

All I had to do was comment out the loopback only restriction and php’s mail() fuction started working great!

vi /etc/mail/sendmail.mc

look for:
DAEMON_OPTIONS(`Port=smtp,Addr=127.0.0.1, Name=MTA')dnl

change it to this:
dnl DAEMON_OPTIONS(`Port=smtp,Addr=127.0.0.1, Name=MTA')dnl

remake the sendmail.cf file
m4 /etc/mail/sendmail.mc > /etc/mail/sendmail.cf

restart sendmail:
service sendmail restart