I have a mail server sitting inside the PIX DMZ, I have intermittent outgoing mail failure issue. For those mails that failed, I can ping the Host on the firewall, but when I tried to ping it on the mailserver, I can't ping the host.
Could it be that the PIX is blocking the access? why some mails can go through while others don't. I have rebooted the PIX but to no avail.