mail routing error, their problem or mine?

[Postmaster]

Any clues to what is going on here anybody - thank you in advance! We're
hosting the web site for this company on our solaris box. Both primary
and secondary DNS is provided by AT&T. The client is running their own
mail server called pines1.pinesofcarolina.org. Mail generated by a CGI
script on our web server is going into dead.letter. When we run a
verbose test from the command line here's what it says:

# mail -v trnreg at pinesofcarolina.org
Subject: test
test please ignore
.
EOT
# trnreg at pinesofcarolina.org... Connecting to mail.pinesofcarolina.org.
via esmtp...
trnreg at pinesofcarolina.org... Host unknown (Name server:
mail.pinesofcarolina.org.: host not found)
/home/dodad/dead.letter... cannot open /home/dodad/dead.letter:
Permission denied
cracker... Connecting to local...
cracker... Sent

#


here is their dns record here:


#  more pinesofcarolina.org.hosts
@      IN      SOA      dns.resell.net. postmaster.resell.net. (
96091552;Serial
36000;Refresh 1 hour
36000;Retry   1 hour
36000;Expire  1000 hours
36000 )      ; Minimum 1 hour

                        IN  NS     dns.resell.net.
;                       IN  NS     ns2.resell.net.

;
localhost               IN  A      127.0.0.1
;

pinesofcarolina.org.      IN      A      207.226.185.63
www.pinesofcarolina.org.  IN      MX      10 pines1.pinesofcarolina.org.

pinesofcarolina.org.      IN      MX      10 pines1.pinesofcarolina.org.

www         IN      CNAME      pinesofcarolina.org.
ftp         IN      CNAME      pinesofcarolina.org.