[otrs] Reply-to address

Does anyone know how I can jerry rig my otrs installation to do this... I want all outgoing messages to replace the normal from: address with "helpdesk@domainxyz.com" and leave the reply-to address as the otrs address that it normally has as the from. basically, if the messages from my otrs box are from otrs@info-sys.domainxyz.com I want it to replace the from: address with helpdesk@domainxyz.com and leave the reply-to address as otrs@info-sys.domainxyz.com We aren't using this box for anything else (related to email, that is) except for otrs. Other apps, but not utilizing email. Using Suse 9.1 and postfix.