Hi, Here's my scenario:- I have roaming users and I don't want to be an open relay, but I cannot predict where these users are. I need a way for them to say to the SMTP server "hey I belong here, let me send email". At the moment, I'm just adding their current IP to /etc/postfix/main.cf (mynetworks) to allow to them send their email. I did a search on google and found that a simple solution will be to use smtp authentication. So I thought I ask you guys I've setup my debian server according to The Perfect Setup - Debian Sarge . Is smtp authentication enabled already? Many thanks!