[exim] attempting to change smarthost

Hello,
I have inherited a Debian box (kernel 2.4.31) running exim4. Our enterprise
SMTP gateway is changing, so I need to adjust the smarthost configuration to
point at the new gateway.

I edited /etc/exim4/update-exim4.conf.conf and changed the dc_smarthost
entry to the new gateway name. Then I ran "/usr/sbin/update-exim4.conf" and
"/etc/init.d/exim4 restart". After that, all mail sent from the machine
just sits in the spool. A new exim4 process is spawned for each mail, but
it just sits out there. If I revert back to the old smarthost and restart,
mail flows normally.

Does the smarthost need to be changed in some other configuration file
also? Is there a debug flag I can add to the exim4 daemon to make it send
more information to the mainlog?

Thanks in advance!
Dave