I need help configuring my postfix mail server. My existing postfix configuration is crap, and I'm getting very frustrated.

Postfix needs to allow relaying for authenticated users. I'm using pam and shadow for authentication. The problem is one of my remote clients has installed a DoS virus on his/her computer. My server is sending a massive amount of spam aimed at some domain in China. (Don't worry, I've disabled postfix so it's no longer an issue)

I can't figure out the source of the problem, because all mail headers appear to be spoofed. I don't think its a remote DoS because postfix will not send messages unless the user is authenitcated, which is why im almost sure it's coming from one of our users.

How can I configure postfix to filter our these junk emails? The recipient domain and ip keep changing, so that rules out blocking the ip or domain. I've tried to setup smtp_client_restrictions but I haven't had any luck.

Does anyone know of a good book or site that will walk me through a good, secure postfix configuration? All of the tutorials I've found have been pretty vague. And most only allow relaying for permit networks (ie: 127.0.0.0/8 192.168.X.X). I need remote users to be allowed to send to outside domains, but I also need to be able to control junk relaying in the event they install an email virus.

Any help would be greatly appreciated.

OReilly has always given me very in depth information on whatever subject the book is for (currently following a BIND and DNS book). You may want to checkout their Postfix book.

To control junk, I'd check into SpamAssassin and along with it a good AV, like clamav. There are hundreds of how-to's written on these very combinations.

Cool