Related terms


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SPF (Sender Policy Framework)

A Sender Policy Framework (SPF) record is an authentication protocol that validates that a message has been sent from an IP address authorized by the sender, helping to prevent fraudulent use of their subscriber list.

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What is an SPF record?

The SPF protocol uses a text file hosted in the DNS (Domain Name System) of the sender's domain. It's a line of code that specifies which machines are under that IP and can send messages with that domain name. The registrar can facilitate the setup from their control panel, or it can be done manually.

The resulting code typically looks like this: []. IN TXT "v=spf1 mx ptr ~all"

You can also explicitly specify an IP address, which would look something like: v=spf1 ip4:[yourIP] ~all

The "all" portion indicates that all other IP addresses are not valid and should be rejected.

How does SPF work?

The authentication process according to the SPF protocol is a standard procedure that follows these steps:

  1. The sender sends a message from their domain.
  2. When it reaches the recipient's incoming mail server, it checks the SPF records to see if it's authenticated, meaning it searches for the domain in the list of valid senders.
  3. The result can be positive or negative, directly affecting your sender reputation.
  4. Message delivery is conditional upon this reputation and can be accepted to place it in the recipient's inbox, marked as spam, delayed for further evaluation, or blocked.

To check if you have your SPF record properly configured, you can look for the code in the header of your last newsletter.

Why is SPF important?

Specifying to incoming mail servers which domains to accept and which to reject is a good practice for three reasons:

  • It ensures good deliverability, meaning it helps avoid landing in spam folders. If the sender can't be authenticated, there's a higher chance of non-delivery.
  • It prevents identity spoofing, as seen in cases of spoofing, because ISPs use SPF records to detect addresses attempting to send messages while pretending to be another sender.
  • It enhances your reputation in the eyes of the recipient, who receives less spam and no deceptive messages from your end.
  • Implementing a policy to authenticate senders is complemented by other protocols like DMARC and DKIM to prevent fraud that could harm your email marketing efforts and results.