I looked at my logs last night after trying to send some messages from
my subsidiary machine (nyarlathotep) to my sendmail server (cthulhu).
Here's what I found:

Apr  9 07:54:13 cthulhu sendmail[3941]: g39CsDc03941: tcpwrappers (nyarlathotep, 192.168.0.14) rejection
Apr  9 07:54:13 cthulhu sendmail[3941]: NOQUEUE: nyarlathotep [192.168.0.14] did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA

I'm not sure why this happened, and reading the xinetd man pages isn't
helping.

I assume from the above that tcpwrappers refused the connection FROM
nyarlathotep, rather than nyarlathotep refusing a connection (auth)
from cthulhu.  Does that sound right?

Can anyone explain to a User With Very Little Brain why this happens?
I didn't believe that sendmail was going to be hidden behind
tcpwrappers --- I thought it relied on its own authentication.

Sounds like I need to add an xinetd config form to permit machines in
my local subnet (only) to get at cthulhu's sendmail server.  Does
anyone have such a form?  Looked for one on google, but couldn't find
anything that fit.

thanks,
R