You can use multiple DNS blacklists with LiveConfig, they’re all checked in order of their appearance. Only use serious DNS blacklists which fulfill requirements like But be careful when selecting a DNS blacklist - it might decide which e-mails are allowed and which are rejected to your server. There are numerous DNS blacklists available, most of them for free. Edit the settings of Postfix: DNS Blacklist

To enable and configure spam filtering, log in as admin and go to Server Management -> Mail. So the goal is to filter out as much spam as possible before running the “expensive” content checks. The order is very important: a DNS blacklist check is very lightweight and can easily be done for hundreds of connections at the same time, while a content analysis is very resource-hungry. The higher the score, the more likely the mail is “spam”. Every “normal” mail server retries e-mail delivery, many SPAM sender do not (because of performance).Į-Mails of large, well-known senders (like Google Mail, Microsoft, and so on) can be accepted immediately by configuring a DNS Whitelist.Ĭontent Analysis - the mail content is checked using a large list of rules, resuling in a certain score. Greylisting - if an e-mail from an (up to now) unknown sender IP is being received, it is temporarily rejected for some few minutes. If the sender is known to be a spammer, the mail is rejected with an appropriate error message. Ideally, there are several levels of spam filtering:ĭNS Blacklist - the IP address of every incoming e-mail connection is checked (in real-time) against one or more DNS blacklists. This documents describes how spam filtering with LiveConfig works, and gives some hints on improving the spam detection rate.

Spamassassin whitelist