The sendmail config file is /etc/mail/sendmail.mc.
This line in the file prevents other machines from accessing your server.
Code:
dnl #DAEMON_OPTIONS(`Port=smtp,Addr=127.0.0.1, Name=MTA')dnl
Uncomment the line to allow other systems to access your system ( send mail to it ).
Code:
DAEMON_OPTIONS(`Port=smtp,Addr=127.0.0.1, Name=MTA')
From the command line:
Code:
make -C /etc/mail/
service sendmail restart
If that is not the issue make sure that the DNS MX record reflects the correct server.