What is the minimum configuration to postfix that I need to do (i.e. to its main.cf file) in order to have the following:

mail go from user1 on comp1 to user2 on comp2 on same lan

demonstration:

user1@comp1# Mail -v "" user2@comp2.somelan.com
hi there
[CONTROL-D]
....
resulting in new mail for user2 under comp2' /var/spool/mail folder

I've been through a bunch of mail server howtos, and they seem to want people to set up full blown domain mail servers with tls security (I even manage to set one up, with postfix and saslauthd running with no errors in log files
just that . . .
it seems to only handle local mail still and not mail from another computer on same network to it.

So, can anyone give me a hand?

cheers

<edit> .. assuming comp1 can resolve comp2, else use the comp2 ip address </edit>

no joy - seems like it queues message, and keeps sending to local accounts' emails instead of other computer

Try a restart instead of a reload maybe...