Sendmail nightmare

Hello all
I'm trying to configure sendmail 8.12.8 on my linux box (RH9), but it
simply drives me nut.
Here are the facts :

I have 4 boxes : 3 (virtual) are standard RH9, 1 (physical) is FC2

Box Nagios Multilink WS-1495 RH9TEST

Type Virtual Virtual Real Virtual
Installed on ESX 2.1.2 ESX 2.1.2 Workstation VMware WS4 on WS-1495
VMTools installed installed -- installed
OS RH9 RH9 FC2 RH9
Sendmail 8.12.8 8.12.8 8.12.11 8.12.8
Iptables No No No No
Sendmail works No No Yes Yes

On all my boxes, I use the default out-of-the-shelf configuration.
The problem arose with sendmail ; I just want to send to my mail hub
(a NT box).
The two RH9 on ESX refuse to send any mail.

Here are some facts :

- I replaced sendmail's config files by those from my FC2 box : same
status.
- I can send messages locally (mail root)
- I can "telnet mailhub 25" from all the boxes
- but, when I try :

# cat /etc/hosts|mail -v -s Hello anyname@anydomain
anydomain: Name server timeout
anyname@anydomain... Transient parse error -- message queued for
future delivery
anyname@anydomain... queued

The error comes from the DNS. A little sendmail testing session gives
more details :

(ON WS-1495, FC2 on my workstation)

# sendmail -v -bt -d21.20,8.20
ADDRESS TEST MODE (ruleset 3 NOT automatically invoked)
Enter <ruleset> <address>
> /mx axa-canada.com
getmxrr(axa-canada.com, droplocalhost=0)
getmxrr: res_search(axa-canada.com) failed (errno=0, h_errno=4)
dns_getcanonname(axa-canada.com, trymx=0)
dns_getcanonname: trying axa-canada.com. (AAAA)
NO: errno=0, h_errno=4
dns_getcanonname: trying axa-canada.com. (A)
NO: errno=0, h_errno=4
dns_getcanonname: trying axa-canada.com. (MX)
NO: errno=0, h_errno=4
dns_getcanonname: trying axa-canada.com.axa-canada.com (AAAA)
NO: errno=0, h_errno=1
getmxrr(axa-canada.com) returns 0 value(s):

(ON NAGIOS, RH9 on ESX)

# sendmail -v -bt -d21.20,8.20
ADDRESS TEST MODE (ruleset 3 NOT automatically invoked)
Enter <ruleset> <address>
> /mx axa-canada.com
getmxrr(axa-canada.com, droplocalhost=0)
getmxrr: res_search(axa-canada.com) failed (errno=111, h_errno=2)
getmxrr(axa-canada.com) returns -1 value(s):

(ON RH9TEST, RH9 on WS4)

# sendmail -v -bt -d21.20,8.20
ADDRESS TEST MODE (ruleset 3 NOT automatically invoked)
Enter <ruleset> <address>
> /mx axa-canada.com
getmxrr(axa-canada.com, droplocalhost=0)
getmxrr: res_search(axa-canada.com) failed (errno=0, h_errno=4)
dns_getcanonname(axa-canada.com, trymx=0)
dns_getcanonname: trying axa-canada.com. (AAAA)
NO: errno=0, h_errno=4
dns_getcanonname: trying axa-canada.com. (A)
NO: errno=0, h_errno=4
dns_getcanonname: trying axa-canada.com. (MX)
NO: errno=0, h_errno=4
dns_getcanonname: trying axa-canada.com. (AAAA)
NO: errno=0, h_errno=4
dns_getcanonname: trying axa-canada.com. (A)
NO: errno=0, h_errno=4
dns_getcanonname: trying axa-canada.com. (MX)
NO: errno=0, h_errno=4
getmxrr(axa-canada.com) returns 0 value(s):

- now the weirdest : I copied the files of RH9TEST (my working RH9)
from WS4 to ESX
--there's a VMWare documented procedure to do so--, and simply
rebooted. Sendmail stopped working.
- I tried both virtual network cards on ESX (vmxnet and vmlance) :
same problem.

Here are some lines of /var/log/maillog

(logs from rh9test on WS4 : successfull sending)
Feb 16 15:14:51 rh9test sendmail[9798]: j1GKEp49009798: from=root,
size=58, class=0, nrcpts=1,
msgid=<(E-Mail Removed) domain>,
relay=root@localhost
Feb 16 15:14:51 rh9test sendmail[9800]: j1GKEpj4009800:
from=<(E-Mail Removed)>, size=369, class=0, nrcpts=1,
msgid=<(E-Mail Removed) domain>,
proto=ESMTP, daemon=MTA, relay=rh9test [127.0.0.1]
Feb 16 15:14:51 rh9test sendmail[9798]: j1GKEp49009798:
to=(E-Mail Removed), ctladdr=root (0/0), delay=00:00:00,
xdelay=00:00:00, mailer=relay, pri=30054, relay=[127.0.0.1]
[127.0.0.1], dsn=2.0.0, stat=Sent (j1GKEpj4009800 Message accepted for
delivery)
Feb 16 15:14:51 rh9test sendmail[9802]: j1GKEpj4009800:
to=<(E-Mail Removed)>, ctladdr=<(E-Mail Removed)> (0/0),
delay=00:00:00, xdelay=00:00:00, mailer=relay, pri=30365,
relay=smmtl104.axa.ca. [142.216.40.151], dsn=2.0.0, stat=Sent (
<(E-Mail Removed) > Queued mail for
delivery)

(logs from rh9test on ESX : error)
Feb 16 15:11:17 rh9test sendmail[12226]: j1GKBH8f012226: from=root,
size=57, class=0, nrcpts=1,
msgid=<(E-Mail Removed) domain>,
relay=root@localhost
Feb 16 15:11:17 rh9test sendmail[12226]: j1GKBH8f012226:
to=(E-Mail Removed), delay=00:00:00, mailer=esmtp, pri=30053,
dsn=4.4.3, stat=queued

Please help !!

Francois