If you mail through threads then the return addres should be that which you entered as your forum email address (I'm not sure where the option is offhand as i don't have a 6.x version of threads running anywhere).
As for the mailer daemon emails, not sure, you may tinker with your aliases file (/etc/aliases likely, may be differant on yoru setup), and scroll down to see where messages sent to the mailer daemon are going, if youw ant these to go to your email, change the associated user to your user account. I think by default they go to root.
