Question 1

What is an SPF record?

Accepted Answer

SPF stands for Sender Policy Framework and is a form of authentication that prevents spammers from spoofing your domain and ruining your reputation. It enables you to choose which IP addresses are authorized to send email on behalf of your domain with a TXT record published in your DNS records.
 
It verifies to the provider's mail servers, such as Gmail, Yahoo, or Outlook, that incoming messages came from an authorized source. The SPF alone, however, cannot fully protect your domain from spoofing. Therefore, installing it along with DKIM, BIMI, and DMARC protocols is always recommended. Once the SPF record is created with the correct syntax, you need to look up and validate it to keep it accurate and error-free. You can easily do this using our free SPF record tester.

Question 2

How do SPF records work?

Accepted Answer

Your SPF record contains a list of IP addresses that are allowed to send messages from your domain. When an email arrives at the recipient's mail server, the mail server verifies your IP address by extracting it from the “From” address. If the email is spoofed, it will have a different IP address from the mail servers authorized in the DNS record. This will result in the email being rejected by the recipient mail server.

Question 3

How to create an SPF record?

Accepted Answer

To create an SPF record, follow these steps to define which IPs or senders are authorized to send emails on your behalf:
 
Start with the tag: v=spf1 – this indicates the SPF version and always stays v=spf1.
 
Specify authorized IPs or domains - include the IP addresses or domains allowed to send emails (e.g., v=spf1 ip4:192.162.0.1).
 
Include third-party senders, if you send emails via an intermediary, add include:thirdpartydomainname.com to authorize them.
 
End with the rule: use -all for a hard fail (unauthorized IPs will be rejected) or ~all for a soft fail (unauthorized emails will be marked as spam).
 
An SPF record may not exceed 255 characters in length and may not contain more than 10 include (or lookups) statements.
 
Once your record is ready, publish it through your hosting provider. This ensures that receiving mail servers can verify if a sender is authorized to send emails on behalf of your domain. Use our online SPF record syntax checker to verify whether your SPF record works correctly.

Question 4

Why are SPF records important?

Accepted Answer

Every email marketer should know how important it is not only to implement SPF records but also to optimize and monitor them to protect their sender reputation and keep away from spoofing and phishing attacks. SPF records empower domain owners to specify which IP addresses or subnets are authorized to send emails on their behalf. Establishing these records allows organizations to bolster their defenses against spam and fraud, significantly reducing the risk of malicious senders impersonating their domain.
 
Furthermore, only authorized senders can send mail on your behalf without rejection by mail servers. Make sure you have identified all sending domains, including your primary domain and third-party services, in your SPF record in your DNS records and removed any domain that does not send mail.

Question 5

Why check the SPF record?

Accepted Answer

To get the best results from your email marketing campaigns and avoid being labeled as spam, publish an optimized SPF record and conduct SPF checks frequently. Doing so will help ensure that no unauthorized mail server is sending spam from your domain. Ensure your SPF record is accurately configured and aligned with industry best practices to protect your email reputation and improve deliverability with our reliable SPF record tester.

Question 6

How does SPF impact email deliverability?

Accepted Answer

The Sender Policy Framework is an essential email authentication protocol that improves email delivery by authenticating incoming messages. It allows certain IP addresses to send emails on behalf of a domain, thereby ensuring that the mail servers receiving them are more trusted, which results in higher deliverability rates.
 
SPF is also vital to achieving DMARC compliance, which helps maintain a positive email reputation and ensure that authentication protocols are followed. Implementing SPF alongside DKIM ensures proper authentication and protection against spoofing or phishing attacks, leading to improved overall email performance and greater deliverability.

Question 7

What is the syntax of the SPF record?

Accepted Answer

ip4 – shows the IP address of a sender in Internet Protocol version 4 (IPv4) or the specified IPv4 subnet on which it is located
 
ip6 – specifies the IP address of a sender in Internet Protocol version 6 (IPv6) or the specified IPv4 subnet on which it is located
 
mx – shows that if the domain name has a mail exchanger (MX) record, it must match the sender's source domain
 
a – if a sender has an address record (A or AAAA), it should be recognized as the sender's address
 
The GlockApps SPF Record validator performs an SPF record syntax check to ensure that it is correct and does not contain any errors that lead to email authentication errors and disrupt email deliverability.

Question 8

What errors can be found in an SPF record?

Accepted Answer

SPF records can contain several types of errors that can affect email deliverability and authentication. The most common issues include:
 
Syntax errors: Incorrect formatting or typos in the SPF record can lead to validation failures.
 
DNS lookup limit exceeded: SPF records are limited to 10 DNS lookups, exceeding this limit can cause the SPF record to fail.
 
No SPF record: If a domain does not have an SPF record, it cannot indicate authorized senders, resulting in potential spoofing.
 
Multiple SPF records: Having more than one SPF record for the same domain can cause confusion and lead to SPF validation errors.
 
Invalid mechanisms or modifiers: Using invalid or unsupported mechanisms and modifiers in an SPF record can lead to failures.
 
An SPF violation is a primary risk that prevents your emails from being sent promptly. Check if your SPF record is properly formatted with our SPF lookup service.

Question 9

What is the correct example of an SPF Record?

Accepted Answer

When you’ve finished setting up your SPF TXT record, it should follow this example:
 
v=spf1ip4:40.1154.301.802 include:thirdpartydomainname.com ~all
 
The TXT SPF record above begins with the version, followed by the authorized IP address, then the third-party domain is included (if you use one) and finished with a tag -all.
 
This is another sample of how your SPF record may look like:
 
v=spf1 a mx ip4:40.1154.301.802 include:thirdpartydomainname.com ~all
 
In this case, the specific domain uses the “a” and “mx” mechanisms, so they are included in the TXT record.

Question 10

Are there any best practices for using SPF?

Accepted Answer

Only include relevant sources: Only add sources to your SPF record if the referrer domain belongs to you. For third-party ESPs, such as ESPs, you do not need to add their “include” to the SPF record.
 
Use the “~all” or “-all” mechanisms: Avoid using “+all” or “?all”. “~all” and “-all” indicate SPF errors, while “+all” whitelists all sources, and “?all” is neutral.
 
Avoid the “redirect=” mechanism: It can limit the addition of other sources. Instead, use “include:” and other mechanisms to list all authorized email sources.
 
Use IP Addresses for Third-Party ESPs: For domains hosted on ESPs like Google, Microsoft, or Zoho Mail, avoid using MX and A records and use a list of IP addresses instead. You can also use the “include” mechanism provided by these ESPs.
 
Implement DKIM and DMARC: It improves email deliverability and protects against spoofing and phishing attacks.

Question 11

How to troubleshoot SPF authentication failures?

Accepted Answer

Verify that the SPF record configuration is correct by using our SPF record syntax checker. Confirm that all authorized IP addresses and sources are listed.
 
Check that the IP address is authorized to send emails on behalf of the domain if SPF authentication fails for a specific IP address. Test the SPF record to ensure the IP address is listed, or whitelist it if necessary.
 
Review the email headers for clues about why SPF authentication is failing. Look for the “Received-SPF” header to see the result of the SPF check.
 
If SPF alignment is failing, the problem might be related to the ESP portal. Make sure you're using the correct domain for the sender's email address in the ESP portal.

Question 12

Are multiple SPF records allowed?

Accepted Answer

No, multiple SPF records are not allowed. According to the RFC 7208 standard, a domain must have only one SPF record. If multiple SPF records are found, they will cause a permanent error, leading to SPF authentication failures. Instead, you should consolidate all SPF information into a single record. Verify the SPF record of your domain with our service to ensure compliance and avoid errors.

Question 13

What happens if you have more than 10 SPF lookups?

Accepted Answer

If you come across the SPF with too many included lookup errors, then your email messages can fail SPF inspection, which can give rise to email deliverability issues and degrade your domain reputation.
 
If an SPF record exceeds the limit of 10 DNS lookups during evaluation, many receiving email servers will either truncate the SPF record or fail to process it altogether. This limitation is imposed to prevent excessive DNS querying, which can lead to delays in email delivery and potential failures. To avoid this issue, it's crucial to optimize your SPF record by consolidating multiple lookups using mechanisms like "include" or reducing unnecessary DNS queries where possible.

Question 14

How do I fix an excessive number of SPF lookups?

Accepted Answer

To fix an excessive number of SPF queries, combine them by using fewer enable mechanisms, or switch to using IP addresses instead of hostnames whenever possible. This will reduce the number of DNS queries needed to effectively authenticate your emails.
 
You can solve the SPF problem of too many DNS queries using SPF record flattening. This technique replaces the nested "include" statements in your SPF record with the corresponding IP addresses or ranges of CIDR, which stands for Classless Inter-Domain Routing, which groups addresses under a common prefix and bit count. This reduces the number of DNS queries required for SPF validation, ensuring that emails can pass validation even if the original record exceeds the 10 DNS lookup limit. In addition, SPF record flattening reduces the risk of SPF check failures due to DNS query timeouts or temporary server issues. If you don't know how to check your SPF record and find any errors, simply use our free online SPF test.

Question 15

What is an SPF PermError?

Accepted Answer

An SPF PermError is a common issue. It occurs when there's a permanent error in the SPF record syntax that prevents proper evaluation. This error indicates a serious problem that cannot be resolved by waiting and typically requires corrective action in the SPF record itself. Common causes include syntax errors, exceeding DNS lookup limits, or incorrect SPF record formatting. To resolve it, review and correct the SPF record with our checker to ensure it adheres to specifications and best practices.

Question 16

Is the SPF Record Checker tool free to use?

Accepted Answer

Yes, our SPF record checker tool is completely free to use. There are no hidden charges or limitations. Try it today to control your domain security and improve email deliverability.

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