Error while sending email from solaris

Dears,

I have tried to send email, but i have following error.
051 mydomain.net: Name server timeout
i have add following line to /etc/resolv.conf

domain mydomain.net

But didn't work, i didn't configure anything else ..
Do i need to configure anything else ????

root#xxx@mydomain.net... Connecting to [127.0.0.1] via relay...
220 SERVER123. ESMTP Sendmail 8.13.7+Sun/8.13.7; Thu, 5 Mar 2009 17:20:32 +0500 (PKT)
>>> EHLO SERVER123.
250-SERVER123. Hello localhost [127.0.0.1], pleased to meet you
250-ENHANCEDSTATUSCODES
250-PIPELINING
250-EXPN
250-VERB
250-8BITMIME
250-SIZE
250-DSN
250-ETRN
250-DELIVERBY
250 HELP
>>> VERB
250 2.0.0 Verbose mode
>>> MAIL From:<root> SIZE=58
250 2.1.0 <root>... Sender ok
>>> RCPT To:<xxx@mydomain.net>
>>> DATA
051 mydomain.net: Name server timeout
050 <xxx@mydomain.net>... Transient parse error -- message queued for future delivery
051 mydomain.net: Name server timeout
250 2.1.5 <xxx@mydomain.net>... Recipient ok (will queue)
354 Enter mail, end with "." on a line by itself
>>> .
050 <xxx@mydomain.net>... queued
250 2.0.0 n25CKWAl029795 Message accepted for delivery
xxx@mydomain.net... Sent (n25CKWAl029795 Message accepted for delivery)
Closing connection to [127.0.0.1]
>>> QUIT
221 2.0.0 SERVER123. closing connection