send mail between two local computers

[scar]

i want to be able to send mail between two computers on the same local
network, simply with the 'mail' command, that cron jobs and other
services use also.  both systems are ubuntu 10.04.

for example the two computers are home1 and home2.

home1 and home2 both resolve to different 192.168.1.X addresses

so i used `sudo dpkg-reconfigure exim4-config` to config home1 and home2
as "mail sent by smarthost; received via SMTP or fetchmail":

System mail name: home1
IP-addresses to listen on: <blank> (so it would listen on all interfaces)
Other destinations: <blank>
Machines to relay mail for: <blank>
IP address or host name of the outgoing smarthost: home1
Hide local mail name in outgoing mail? <No>
Keep number of DNS-queries minimal (Dial-on-Demand)? <No>
Delivery method for local mail: mbox format in /var/mail/
Split configuration into small files? <No>

likewise i did the same config on home2 except i used "home2" where i
used "home1" above.

now when i try to send mail:

scar at home1:~$ mail scar at home2
Subject: foo
foo
.
Cc:
scar at home1:~$

i get a bounce message from postmaster:

Subject: Message frozen

Message 1QlBIc-0005Jt-G0 has been frozen.
The sender is <scar at home1>.

The following address(es) have yet to be delivered:
  scar at home2: remote host address is the local host

even if i try using the command `mail scar at 192.168.1.X` i get the same
error.