[NTLUG:Discuss] weird sendmail domain problem

[kbrannen@gte.net]

I've been working on RH7.2 (fully patched) machine with the weirdiest sendmail 
(v8.11.6) error I've ever seen...and I'm looking for any ideas.  Yes, I'm 
sorta desparate. :-)

Whenever anyone from the outside sends email to this machine, it replies with:

553 Requested action not taken: mailbox name not allowed

But if you are on the machine and email, it works fine.  It's as if it doesn't 
know what domain it belongs to.  Yes, I've got the domain in the 
/etc/mail/access and /etc/sendmail.cf files.  Yes, hostname -f returns the 
correct value (now, it didn't before I worked on it, plus a reboot).

One other clue is that it used to work correctly.  Then the machine got moved 
to another location with a new IP address.  Yes, a nslookup on both the domain 
name and the FQDN of the machine produce correct answers, both on the machine 
and off (from my home machine).  Still, deep down, I believe this to be a DNS 
thing; I just can't prove it.

Testing with telnet produces (IP & addresses changed to protect from SPAM):

$ telnet 1.1.1.1 25
Trying 1.1.1.1...
Connected to 1.1.1.1.
Escape character is '^]'.
220 SMTP service ready
helo gte.net
250 Requested mail action okay, completed
mail from: k at gte.net
250 Requested mail action okay, completed
rcpt to: root at f.com
553 Requested action not taken: mailbox name not allowed
quit
221 SMTP server closing transmission channel
Connection closed by foreign host.

Anyone have any clues?  I found all kinds of interesting sendmail things on 
Google, but none of it helpful. :-/

TIA,
Kevin