Check your sendmail.cf for entries for DR and DH also.
Check the output of this command:
/usr/lib/sendmail -d0.1 -bt < /dev/null
(post the version of sendmail you are using and the version of Solaris)
And mail14.messagelabs.com does exist - it's at 212.125.75.19. Somewhere, your mail is configured to send mail there.
Also answer these questions:
Is this a new server? (yes or no)
Has email EVER worked on this server? (yes or no)
If yes to last question - what changed?
Check the
sendmail support page for more info.