What Is SPF, and Why Is It Necessary for Your Business Email?
Sender Policy Framework (SPF) is a protocol used to authenticate email senders. It helps detect and prevent email spoofing and other forms of unauthorized use.
More specifically, SPF allows only specific legitimate IPs to send emails on behalf of your domain. The SPF policy is defined in the DNS record and includes all the authorized mail that can successfully send emails from your domain name.
The IP addresses that try to send an email from your domain name but are not listed in the DNS record will not reach the intended primary inbox. It’s a list of verified, authorized attendees who are permitted to join the private party. Anyone who is not on the list can’t join the party.
The list can be accessed and viewed publicly. It can also be retrieved by receiving servers for authentication purposes, as outlined under RFC 7208. But why is SPF so important for business emails? Let’s find out together!
Key takeaways:
- SPF is a standard email authentication protocol that allows you to detect and prevent various forms of unauthorized use.
- Implementing SPF correctly comes with numerous benefits, including higher email deliverability, lower bounce rates, reduced spam, and an improved sender reputation.
- SPF also has some limitations, including restrictions on lookup and string character counts, as well as a lack of reporting capabilities.
- You can easily overcome many of the SPF challenges and limitations by following best SPF practices and combining its use with other protocols, such as DMARC and DKIM.
- There are free online tools that can make it easier for you to generate and validate your SPF record.
The Significance of SPF for Email
Billions of spam emails are sent every day. When you generate SPF record, you take a significant step against this malpractice and toward protecting your domain from various cyber threats.
Less Spoofing
When a hacker tries to send an email from your business email name, s/he will most likely face an SPF failure. Preventing malicious actors from impersonating and exploiting domains is the primary purpose of SPF, which is why hackers often face these failures.
SPF helps verify the legitimacy and authenticity of the sending server, and thereby reduces the likelihood of spoofing success. The reduction in spoofing rates also leads to fewer phishing, spamming, and other forms of dangerous cyber threats.
More Email Deliverability
SPF has a positive impact on email deliverability. The lack of SPF, on the other hand, often results in high bounce rates and delivery failures. This is because recipient servers feel safer accepting emails from authorized sending servers. If you don’t have SPF in place, be prepared to experience low email deliverability and high spam rates, even if your emails are completely safe and legitimate.
Spam Mitigation
With SPF in place, it’s much harder for hackers to impersonate well-known and trusted brands and send illegitimate, malicious emails on their behalf. This leads to a significant reduction in the success of spam campaigns and an improvement in mitigation.
Higher Compliance
Numerous major email service providers have made it mandatory for bulk senders to implement DMARC in email security. Since SPF is an essential component of DMARC, the role of SPF implementation has also increased substantially. Not implementing SPF can lead to compliance issues, which in turn can result in legitimate emails being sent to the spam folder or getting blocked entirely.
No More False Positives
With SPF, receiving servers are less likely to send legitimate emails to spam. This is because, with the list of verified senders, it’s much easier to distinguish between legitimate sources and fake, potentially malicious ones. Taking action accordingly also becomes much easier. This helps you avoid false positives and effectively convey your message to the right people at the right time.
Improved Brand Image
SPF helps build a better sender reputation and also contributes to a more positive overall brand image. Both ISPs and average clients appreciate secure email sending practices and are more likely to do business with those who engage in safe and secure communications. Therefore, SPF is important not only in the email interface but also in many other business areas.
SPF Challenges
SPF, as beneficial as it is, also has drawbacks. Here are some of them.
Too Complex
You may find it challenging to manage your SPF record if the number of authorized email servers continues to increase. This also applies to third-party services; the higher the number of such services, the harder it will be to manage the record.
Difficulties also arise when you engage in email forwarding. Since the IP address of the forwarding server is often not included in the original sender’s SPF record, this can result in an authentication problem and SPF failure.
The Famous Lookup Limit
When you exceed the SPF record limit (capped at a maximum of 10 DNS lookups), you’re likely to experience a permanent error (PermError). This is often the case for businesses that use too many third-party vendors.
Character Limit
Speaking of limits, the lookup cap isn’t the only one. There is a limit of 255 characters to a single TXT record string. Sure, you can have more than a single string within one record, but this can cause difficulties, since it’s hard to take care of so many strings simultaneously.
Lack of Reporting
SPF, as applicable and valuable as it is, lacks an important feature: reporting. Therefore, you can’t obtain insights into your authentication failures. This necessitates combining SPF with other email authentication protocols, such as DMARC.
Sending Server Authentication
SPF is explicitly designed to authenticate the sending server by checking the Return-Path domain. It does not offer encryption, ensure the integrity of the message content as DKIM does, or directly validate the user-facing “From” address seen by recipients. This means attackers may exploit SPF by sending messages from an authorized server while spoofing the visible ‘From’ address.
Workarounds for Common SPF Problems
To avoid SPF challenges and false positives, follow the best practices below.
Use One SPF Record Only
Avoid using too many SPF Records and focus on a single SPF TXT record. Combining all your authorized senders into one comprehensive record will help you avoid validation problems and benefit from a healthy and happy SPF.
Pay Attention to the Syntax
Many don’t pay sufficient attention to syntax mistakes and inappropriate mechanism usage, but these can result in major SPF issues and negatively impact your email deliverability. For example, if you use `TXT` instead of an `include` mechanism in a place where the usage of `include` was necessary, don’t be surprised to experience SPF failures. Therefore, it’s essential to check your SPF before you publish it.
Updating on Time
Update your SPF record regularly when changing email providers or modifying services. Failing to update records on time can result in serious security gaps, opening the doors for hackers and blocking even safe, legitimate emails.
Respect the Limits
This is true for many things in life, including SPF. Always try to stay within the 10 DNS lookup limit and avoid adding too many mechanisms, such as `include`, `mx`, etc. Also, make sure your record complies with the 255-character string limit. Following these limits and the general DNS record size limit can help you avoid many failures and challenges in your SPF implementation and monitoring journey.
Use the Right Record Type
If you wonder what the proper SPF record type is, keep in mind that it’s TXT. Yes, just TXT. It’s easy to remember and easy to implement.
Include All Authorized Senders
Ensure that you include all verified third-party services in the list, so that your ‘party list’ consists of all relevant attendees and does not block the entry of the people you love and cherish. This will ensure better relationships, improved communication, and a more enjoyable party overall!
How to Set Up SPF For Your Email
Here are the steps you should follow to set up SPF for your email.
- Identify the Authorized Servers
Compile a complete list of all IP addresses or hostnames for email servers permitted to send messages on behalf of your domain. This should include your organization’s mail servers, any third-party email service providers (such as Google Workspace, Microsoft 365, SendGrid, Mailchimp, etc.), and any other services that use your domain to send email. Ensure the list covers all authorized sending IP addresses and domains.
- Determine Your SPF Policy
Next, decide what SPF policy you want to have in place. In this step, you mention the exact servers allowed to send emails on your domain’s behalf and determine how the receiving servers should deal with the email. You will do so with the help of the qualifiers, which include `-all` for Fail and `~all` for SoftFail.
- Choose the Right Format
You now know what format is right for SPF, don’t you? Correct, all SPF records should be a TXT record, published in your domain’s DNS. The record should start with ‘v=spf1’, include the necessary mechanisms and modifiers, and end with the ‘all’ mechanism and its qualifier.
- Time to Get Published
Now, you should publish the record. For this, generate an SPF record either manually or with the help of a free SPF generator tool. Then, find the DNS settings for your domain in your domain’s DNS management system and add a new TXT record. Here, you’ll need to specify the hostname and then paste the correct SPF record string into the data field. And voilà, you’re done!
- Check your SPF record
Oh, wait, you’re not entirely done yet. We almost forgot one crucial step, as many often do — checking. Once your SPF record is set up, you need to test and check your record. This will eliminate the likelihood of errors and provide you with the peace of mind that DNS servers are recognizing your record.
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Summing Up
SPF has become an indispensable component of email communications for businesses, regardless of their field, size, or objectives. It is a cornerstone of safe and reliable email communications, providing a quick and effective pathway toward increased deliverability, reduced spam, and enhanced online security. Following the best SPF practices and combining SPF with other key email authentication protocols can completely transform your email communications and help protect your business from malicious actors.