[Exim] EXIM Broken after Solaris Upgrade

Having just upgraded our E450 to Solaris 9 I find that EXIM no
longer works as expected. It will no longer send mail to external
addresses automatically. We are using exim-4.04-1 and have changed
nothing prior to upgrading the OS. Simple testing of the
configuration:

#exim -bV
Exim version 4.04 #1 built 06-Jun-2002 11:39:16
Copyright (c) University of Cambridge 2002

...Does not suggest any problems.

I can also send mail manually from the console:

#exim postmaster@???
From: user@???
To: user@???
Subject: test mail

this is a test.

ctrl-D

Sends the message to the external address.

Stuff like cron job confirmations and web based forms which use
the local MTA no longer work. I'm puzzled as everything is as it
was prior to upgrade.

Can anyone point me in the right direction?

Thanks

PaulM.