I am running MS Exchange 2003. Question: if I unselect "Allow all computers which authenticate to relay, regardless of the list above" will the logged on clients be able to send external email?

If you untick that box your SMTP clients will not be able to send at all. "jwatkins60643" wrote in message news:c9ae37e3-d646-4a3b-ac72-e764d35db542... I am running MS Exchange 2003. Question: if I unselect "Allow all computers which authenticate to relay, regardless of the list above" will the logged on clients be able to send external email?Mark Arnold, Exchange MVP.