Mailhandling in rt

Hello,

i am using Version 1.0.7 of rt and Sendmail 8.10. I have set smarthost feature.
Now all mail from rt is comming from rt@host.domain.com but i want it to look
like rt@domain.com.
I don’t want to set NULLCLIENT Feature.
in /opt/rt/etc/config.pm i set the following:

rtname=domain.com
host=localhost
mail_alias=support@domain.com

How do i set the default answer user of rt to another user like support?

Hope you can help me.

Frank