Changing relayhost in application.ini

I was requested to change my relayhost configuration in the applicaiton.ini file, but here are no default settings in the file regarding the relayhost. Normally i would just edit in /etc/postfix/, but this error seems to be asking me to do something different. I get this request when I startup Vimbadmin for the first time, setting the admin email, and when I would like to send a welcome email with Vimbadmin. for a new account.

Thanks for the help