[Koha] SMTP settings for Koha box

I'm using Koha 3.0.0.3 on Suse 11.1 box How to I setup Koha (or Suse Linux) to use our main Mail server (GroupWise) to send out all generated mails ? I don't see any settings in Koha System Preferences Rudy Wuthrich Kodaikanal International School http://koha.kis.in