SPF, DKIM, and DMARC: The Dynamic Trio That Can Save You From Email Fraud and Spam
Email is an essential part of our lives, and we use it to communicate with friends, family, and work colleagues. However, email fraud and spam can be a significant problem, and it’s crucial to have ways to prevent it. Luckily, there are some technologies that can help authenticate the sender’s identity and ensure that the email you receive is legitimate. These technologies are SPF, DKIM, and DMARC.
Let’s start with SPF. It’s like having a bouncer at a nightclub entrance. The bouncer has a list of people who are allowed to enter the club, and they only let those people in. Similarly, SPF allows the domain owner to publish a list of IP addresses that are authorized to send email messages on behalf of their domain. When an email is received, the receiving server checks the SPF record of the sending domain to verify that the IP address of the sender matches the authorized list. If it’s not on the list, the email is rejected or marked as spam.
Now, let’s talk about DKIM. Imagine that the sender of an email message has a wax seal with their initials on it. DKIM is like that wax seal. The sender adds a digital signature to the email header using a private key, and the receiving server uses a public key published in the sender’s DNS records to verify the signature. If the signature is valid, the email is considered authentic and is delivered to the recipient’s inbox. This way, even if the email is modified in transit, the digital signature will be invalidated, and the email will be marked as spam.
Lastly, we have DMARC. DMARC is like having a security guard who knows how to check IDs at the nightclub entrance. DMARC is a protocol that combines SPF and DKIM to provide an additional layer of email authentication. It works by allowing domain owners to specify how SPF and DKIM should be used to authenticate emails from their domain, and how the receiving server should handle emails that fail authentication. DMARC policies can be set to three different levels: monitor, quarantine, or reject. When a receiving server receives an email with a DMARC policy, it checks the SPF and DKIM authentication results and follows the policy specified by the domain owner.
By using these technologies together, we can prevent email fraud and spam. SPF verifies the IP address of the sender, DKIM verifies the authenticity of the email message, and DMARC provides a policy for how to handle emails that fail authentication. While SPF and DKIM are mandatory for DMARC, they can also be used independently. In other words, these technologies work together like a team to ensure that the emails you receive are legitimate and safe to open.
Update:
I have created a PowerShell script that will automatically check if the proper DNS record exist and provide you the required records in the event that they don’t. It can be found on my github repo.
