Saturday, October 20, 2007

Systems Part 2

While last time we talked about the mail hub, this time I'm going to talk about our Spam and Virus pass through server. This server also runs qmail but has no local mailboxes. With qmail we use smtp routes to deliver mail to clients that have their own mail server. This lets us be their front end to the internet and spam and virus scan. It is like a gateway spam and virus filter. Except it is on a larger scale. It will also allows all the clients with exchange servers to take their server down, and we will hold the mail for a time.

Incoming email is handled by magic mail smtpd. With this we are able to maintain a list of valid users and keep from just accepting email for any address. Once this is done it is handed off to qmail-scanner-queue.pl. This runs ClamAV and Spamassassin on the message. We quarantine virus and mark spam in the subject.

Why do we only mark spam? Well because all email must be delivered. While on the previous server we maintain the mailbox and can create a .Spam folder that is not downloaded via pop3 we can't do that with this server. All our servers are designed to fail open. To always give the client their email. With clients like law firms, financial institutes, and engineers we do not want to stop any email from getting to them.

Some clients are just to big to do this, or they have special circumstances and need a whole server by themselves. I also have several of these and I will in a later post go into detail as to what some of the custom setups.

I know your waiting on the configurations, and that is coming up. So hang in there.