I successfully followed the guide at http://www.howtoforge.com/virtual-users-and-domains-postfix-courier-mysql-centos5.1 However, emails are sent out as being From email@example.com rather than firstname.lastname@example.org. I think this is causing SPF problems because SPF is matching on machine.domain.com rather than domain.com. I tried setting the $myorigin directly to 'domain.com' but that didn't seem to effect the From after restarting postfix. Is there some other service I need to restart? Or is there another variable I need to change? It seems like there should be a virtual domain way to do it (although it's not necessary for me).