In this video, Chaim Krause discusses the Sender Policy Framework and using a simple TEXT resource record in a domain's DNS can help with reducing SPAM
- [Instructor] SPF, sender policy framework. It's one of the first attempts at stopping unsolicited email by taking a proactive approach. We've seen spam assassin look at emails when they're received. With sender policy framework, you actually state these are my servers and you shouldn't accept email from anybody else. The reason you want to use SPF is to let other email administrators who are receiving email detect if it's spoofed.
The way you do that is by telling the other administrators through an entry in DNS that hey, if the email is not from one of these servers that I've listed here, then it's being spoofed. It's defined in publication RFC 7208, and you can find more information at this address. All it is is a simple TXT or text entry in the DNS. If we look at this example.com here, the text record simply says v for version, spf1.
Next it says if there's an a record in this domain or the sender of the email, then it's good. Otherwise, for all others, it's a spoof. This is the first attempt at this effort.
- Reviewing the components of email delivery
- Sending mail with Postfix internally and externally
- Configuring TLS, SASL, and an email client
- Installing database tools
- Creating virtual domains, users, and aliases
- Exploring greylisting with Postgrey
- Installing and configuring spam tools
- Reviewing DNS-based protection against spammers