Help on sendmail

[W. W. Looi]

We have a RS6000 530 data server, a 320H gateway and a 320H compute
server running AIX 3005, NFS, and NIS. I was able to send mails from
the 320H gateway to the 530 data server and 320H compute server, but
wasn't able to send mail from 530 to 320H gateway server.

But, it works if I telnet from 530 to 320H gateway server via port 25,
and compose the mail manually. I.e.

devlgw -> 320H gateway
devlds -> 530 data server

HELO devlds
MAIL From: <root at devlds>
RCPT To: <root at devlgw>
DATA
To: root at devlgw
Subject: testing

This is a test from 530 to 320
.
QUIT
..
..
...

Note that, I have to type in To: root at devlgw and Subject: testing.
Otherwise it won't work. I guess something in sendmail.cf isn't
configured right, but I'm just not knowledgeable enuf' to pursue the
modication. 

Can someone please help? Thanks in advance.