prevent sm to relay a mail to a hostname who is in localhostname...

Hi,

I try to set sendmail on an internal network.
The DNS for the zone is the following.

sombre. MX smtp.sombre.
gandalf A 192.168.3.1
aragorn A 192.168.3.125
dns CNAME gandalf
smtp CNAME gandalf
sombre. CNAME aragorn

The purpose is to have gandalf being a smtp server and aragorn a web
server both on sombre.

All goes well as long as the line "sombre. CNAME aragorn" not appear.
But when i add this line, the sm server try to relay the mail send to
toto@sombre to aragorn at sombre.

Jan 7 22:23:46 deb-server sm-mta[4495]: m07LNkro004495: to= abel@sombre,
ctladdr=root (0/0), delay=00:00:00, xdelay=00:00:00, mailer=relay,
pri=30063, relay=[127.0.0.1] [127.0.0.1], dsn=2.0.0, stat=Sent
(m07LNkro004496 accepted for delivery)

Jan 7 22:23:46 deb-server sm-mta[4499]: m07LNkro004496: abel@aragorn.sombre>, ctladdr= (0/0),
delay=00:00:00, xdelay=00:00:00, mailer=esmtp, pri=120348,
relay=aragorn.sombre. [192.168.3.125], dsn=4.0.0, stat=Deferred:
Connection refused by aragorn.sombre.

The question is : What must i do to prevent sendmail form relaying any
mail to host sombre. and evantually to prevent him even to do a DNS
request on this host. I want to mail to be send localy on gandalf as he
does it when no entry for sombre. exist in the DNS.


Actually, i have a local-host-name file with

#local-host-name

localhost
deb-server.sombre
sombre


Everything else i need to set ?