I'm well aware that sendmail operates on the incoming ports 25 and
587. However, I'm wondering about from what ports sendmail send
outgoing mail from.. does it use 25 still? or does it just use a
random high port? I'm trying create a firewall rule, that would limit
any mail leaving the server unless it was sent through sendmail. (as
opposed to a local user setting up their own smtp server in their pine
or something)

I'm hoping it does use 25 to send outgoing as well, then i could
create a rule to only allow outgoing packets to port 25 IF it is
coming FROM the local port 25..

Any answer here, or any alternative would be great.. just try to limit
outgoing mail..

Thanks
alex