Sender Policy Framework (SPF records) explained

Defines, authorizes, and publicly discloses which mail servers are allowed to send emails from your domain

Spam is one of the biggest problems in the computer world. It has also been following us practically since the first email was sent, and today it makes up the majority of mail traffic on the Internet. Fortunately, there are ways to reduce the amount of spam, and even almost eliminate it, which we try every day with various software solutions.

The overall performance is relatively good, but spammers are still monitoring the situation and trying, in every way, to improve the amount of spam delivered. In a series of tools and ways to combat spam, we will look at the SPF - Sender Policy Framework.

SPF is designed as an authentication system. It is a DNS record in which you define, authorize, and publicly disclose which mail servers are allowed to send emails from your domain - it limits from which addresses mail can be sent so that it contains the domain name in the sender's address. It can also be described as Sender Policy Framework technology that is based on publishing Domain Name Service (DNS) records that determine whether an individual computer is authorized to send an email for a given domain.

We use the SPF to authenticate the user, which enables the determination of whether the sender of the email message is the one for whom he is pretending to be. Sender authentication also brings other benefits to users. In the first place, someone cannot falsify their email address and thus harm the other side. Another problem related to sender authentication is the so-called phishing attacks. These are attacks that, by falsifying the source of a message, try to find out sensitive information from users, such as a credit card number.

Spammers like to set the address "MAIL FROM" from a known server (Google) so that their spam has a better chance of reaching the user's inbox. With the help of SPF, we protect others from emails that allegedly come from our domain, as well as our users who know how to receive mail that allegedly originates from the local domain.

The problem of spam emails needs to be addressed in multiple layers. While completely disabling the sending of spam messages is impossible, every aspect of the antispam initiative makes the sending process increasingly complex, and therefore economically unprofitable. The SPF protocol has shown great efficiency in blocking spam messages in combination with whitelisting/blacklisting, greylisting method, and independent accreditation systems.

The sender of spam messages can bypass the SPF mechanism by registering his domain and implementing the SPF protocol. However, such cases can be prevented by checking blacklists based on IP addresses or domain names.

The popularity of the SPF protocol, among other things, stems from free upgrades for most email servers, which promote the process of implementing the SPF protocol. The protocol itself is very flexible and upgradeable and allows gradual installation. Nowadays, SPF is implemented on a large number of email servers.

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