Understanding SPF Records

May 12, 2023 | Blog, Deliverability, SPF

A Guide to Secure Email Delivery

In today’s digital world, email has become an essential means of communication for individuals and businesses alike. However, the prevalence of email-based attacks such as spam, phishing, and spoofing has raised concerns about email security.

One crucial tool in combating these threats is the Sender Policy Framework (SPF). In this guide, we’ll delve into  understanding SPF records and explore how they can enhance the security of your email infrastructure.

How Does SPF Work?

When an email is sent, the receiving mail server can check the SPF record of the sender’s domain to verify whether the email originated from an authorized server. The process involves the following steps:


  1. The receiving mail server extracts the domain name from the sender’s email address.
  2. It performs a DNS lookup to retrieve the SPF record associated with the sender’s domain.
  3. The SPF record specifies the IP addresses or hostnames of servers authorized to send email for that domain.
  4. The receiving mail server cross-references the IP address of the connecting server with the authorized servers listed in the SPF record.
  5. If the connecting server’s IP address matches one of the authorized servers, the email passes the SPF check.
  6. If the connecting server’s IP address does not match any authorized servers or if no SPF record is found, the email may be flagged as potentially fraudulent.

How to Create an SPF Record?

To create an SPF record for your domain, follow these steps:
  1. Determine the authorized email servers: Identify the IP addresses or hostnames of the servers that are allowed to send email on behalf of your domain. These servers can include your own mail servers, third-party email services, or marketing automation platforms.
  2. Define the SPF record: Compose the SPF record using the appropriate syntax. An SPF record typically starts with a “v=spf1” tag, followed by mechanisms that specify the authorized servers and their authentication requirements. For example, the record may include “include,” “a,” “mx,” or “ip4” mechanisms.
  3. Set up the SPF record in DNS: Access your domain’s DNS management interface (often provided by your domain registrar or hosting provider) and add a TXT record containing your SPF record. Be cautious not to overwrite any existing TXT records as they might be used for other purposes.
  4. Publish the SPF record: Save the changes in your DNS management interface. The updated SPF record will be propagated across DNS servers, typically within a few hours, but it can take up to 48 hours to fully propagate.

Best Practices for Using SPF Records

Consider the following best practices to maximize the effectiveness of SPF records:
  • Monitor email traffic: Regularly analyze your email traffic to identify any unauthorized or suspicious sending sources. Monitoring tools can help you identify anomalies and potential threats.
  • Use “Hard Fail” mechanism: Consider using the “-all” mechanism at the end of your SPF record to specify a strict policy. This instructs receiving servers to reject any emails that do not originate from authorized servers. However, be cautious as this may result in legitimate emails being rejected if not configured correctly.
  • Regularly review and update SPF records: As your email infrastructure evolves, regularly review and update your SPF records to ensure they accurately reflect your authorized email servers.
  • Implement DKIM and DMARC: Supplementing SPF with DomainKeys Identified Mail (DKIM) and Domain-based Message Authentication, Reporting, and Conformance (DMARC) further enhances email security and helps protect against phishing and spoofing attacks. Regularly review and update your SPF records to ensure a robust email authentication framework.

Heysender blog

Read our other blog entries to get new inspiration for your transactional emails.

Phishing: A Threat to Your Inbox and Your Domain

Have you ever received an email that looks like it's from your bank, but something just feels off? That might be a malicious attempt on phishing. Phishing emails are a cunning attempt by cybercriminals to trick you into revealing sensitive information, like passwords...

How a Deliverability Audit Can Save Your Email Marketing Efforts

Investing significant time and effort into crafting compelling email marketing campaigns can be rendered ineffective if those messages fail to reach their intended recipients.  Unfortunately, this scenario is not uncommon. Emails can be relegated to spam folders or...

How Honeypots and Spam Traps Can Sabotage Your Email Campaigns

Ever hit send on a perfectly crafted email campaign, only for it to vanish into the abyss? As an email sender, you live in fear of spam filters and low deliverability rates. Beyond the well-known challenges of spam filters, have you considered the potential impact of...

Unleash the Power of Automation: Using Webhooks in Your Email Platform

Ever wished your email platform could talk to your other business tools? Well, with webhooks, it practically can! Webhooks are a game-changer for email marketers, offering real-time notifications and automated workflows that streamline your campaigns and boost...

The Pitfalls of “No Reply” Emails: Why Engagement Matters

Whether it's a confirmation of a purchase, a receipt for a service, or a password reset, transactional emails play a crucial role in maintaining customer relationships and providing essential information. However, there's a pervasive practice that has found its way...

Optimizing Email Deliverability: The Importance of Domain Warm-Up

In the context of transactional emails, where timely and critical information is exchanged between businesses and users, ensuring deliverability is paramount. Transactional emails, such as order confirmations, account notifications, and password resets, play a pivotal...

The Power of Metrics in Transactional Emails

Transactional emails play a crucial role in fostering customer relationships and facilitating smooth business operations. Unlike marketing emails, which aim to promote products or services, transactional emails are triggered by specific user actions, such as account...

Harnessing the Power of Transactional Emails: Types, Examples and Best Practices

In the ever-evolving landscape of digital communication, transactional emails have emerged as a crucial component in maintaining a seamless and efficient interaction between businesses and their customers. Unlike promotional emails, which aim to market products or...

Boosting Email Visibility: How to Stand Out in the Inbox with BIMI

With inboxes flooded with emails daily, it's crucial for businesses to find innovative ways to capture the attention of their recipients. One effective solution gaining traction is the use of BIMI (also known as Brand Indicators for Message Identification). In this...

New Steps in our Data Security Efforts: Heysender Completes ISAE 3000 Revision

Heysender Gets ISAE 3000 Report The ISAE 3000 report investigates how employees in the organization treats and stores your data, and how GDPR processes are communicated and followed in the daily work.  The revision and report are carried out by an external accountant....