How do you protect against outgoing spam

[chani]

I think there are several ways to do what you want. I guess you don't want to block outgoing mails, you just want to be informed if one of your customers/users is sending spam/viruses. I'd also suggest you to use amavisd together with spamassasin - just configure it in a way that you get a notification on virus/spam alert (look into the amavisd config) if it reaches a specific level -> but don't do filtering. As soon as someone is sending a spam mail you should get a notification about it. If you're only getting one mail it might be a false positive. I guess a real spammer would send a lot more - So if you got 100 mail notifications, you know that something happened. If youre only getting one, you might ignore it

Another option would be to write your own policy-service. On postfix.org you'll find some documentation about it, if needed i'll post the url to the part in their documentation. You might write your own policy-service which is doing just this (checking using spamassasin/clamscan for spam/virus, if it reaches a specific limit send mail notification to you, without even touching the mail at all) this one is a bit tricky, though.

I don't do this at all, i have to trust my customers.