Hi, I'm running Mandriva 2008 One and I've attempted to follow this how-to guide: http://www.howtoforge.com/mandriva_postfix_antispam_antivirus_exchange I'm trying to configure Postfix to scan inbound and outbound smtp mail on my network. We use Exchange 2003 internally on a Windows 2003 domain. I also have an ISA firewall sat at the border, so the Mandriva machine is behind this ISA box. I have email flowing just fine without using the Mandriva box. So when I have Exchange setup to route external SMTP through the ISA server using the IP of the ISA server as a smarthost, it all works fine inbound and outbound. As soon as I set the smarthost IP on the Exchange server to point to the Mandriva machine, email stops flowing. I'm a total newb with Linux, so please be gentle ;-) I don't even know where to look on the Mandriva box to see if mail is being received into any of the queues? I have tried telnetting to the Mandriva box using port 25, and I think it connects - I don't see any message saying it couldn't establish a connection - but I also don't see what I would class as an SMTP connected notice? I have disabled the firewall on the Mandriva box - as a temporary measure, to see if that made a difference but unfortunately it hasn't so far. Any help you can offer is greatly appreciated!!! Thanks and kind regards, Greg.