LTM 11.5 how to change ssmtp root email destination

Thanks for the replies. I've got the smtp server set and that is working fine but the issue is that email destined for "root" is being sent to "postmaster@hostname". I'm looking for the equivalent functionality that is achieved by editing the /etc/aliases file and changing the "root: " line. It seems odd to need an iRule to do this, and looking at it, I don't think it's what I'm looking for.