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SPF Record Checker

What is an SPF Record?

A Sender Policy Framework (SPF) record is a DNS TXT record with all the servers authorized to send emails from a specific domain. The main reason behind the introduction of SPF records is the inability of SMTP to authenticate the "from" email address of an email.

How Do SPF Records Work?

Email receiving servers can verify SPF records by checking the domain's Return-Path value in the email headers. Then this Return-Path is used by the receiving server to search the DNS server of the sender for a TXT record. If SPF is enabled, it will identify all approved servers from which mail may come. The SPF check will fail if that particular IP is not on the list.

It is similar to a guest list of an event. If the guest has their name on the list, they will be allowed to the event. Similarly, if the SPF record does not have the domain or the sender's IP address on the list, the receiving server will not be able to send emails from them.

What Does An Example SPF Record Look Like?

An SPF record has a standard notation. The below example shows the main components that need to be included in an SPF record.

1 v=spf1 ip4=192.0.2.0 ip4=192.0.2.1 include:examplesender.email -all
  • v=spf1
    • Informs the server about the SPF record.
  • ip4=192.0.2.0 ip4=192.0.2.1
    • Authorized guest Ip addresses that the server can send emails on behalf of the domain.
  • include:examplesender.email - Third-party organizations that can send emails on behalf of the domain.
  • -all
    • Informs the server that all the other unlisted addresses should be rejected.

Understanding the SPF Record Results

An SPF record can return several values:

  • Pass - The host is authorized to send from the domain.
  • Fail - The host is not authorized to send from the domain.
  • SoftFail - The host is not authorized to send from the domain during that transition.
  • Neutral - Nothing can be said about validity.
  • None - No SPF record was found for the domain.
  • PermError - A permanent error has occurred.
  • TempError - A transient error has occurred.

What is SPF Record Checker, and How Does it Work?

SPF Record Checker is a diagnostic tool. It checks and validates several elements of an SPF record to assure its accuracy and reliability.

First, it checks for an SPF TXT record in the DNS database of a queried domain name. If there is an SPF record, it will display the contents and the errors. Mimecast DMARC Analyzer, MXToolbox, and Kitterman are some of the most used SPF record checkers.

What is SPF Lookup Used For?

SPF lookups allow you to analyze the SPF record of a domain for errors, security issues, and authorized IP addresses. In addition, you can use it to check if an IP address is authorized to send emails on behalf of a domain.

FAQs

1. I've published my SPF records. What's next?

Test your SPF record using an SPF check tool after publishing the SPF record. The receivers' views will be visible to you with a list of the servers permitted by your sending domain to send emails on your behalf. You can edit your record to include additional IP addresses if they are not already mentioned.

2. How do I correct a failed SPF record message?

First, you must correct the SPF record from the sender's side. For that, make sure the sender's SPF records are correctly configured. Then, if there are any issues, you can contact the server admin and get things resolved.

3. Do I need an SPF record?

Although only a few of your company's domains are used to send emails, SPF records should still be set up for each domain owned by your company to prevent spammers from successfully spoofing any of them.

4. How do I query SPF records with nslookup?

The DNS lookup data is combined with the SPF record, which is kept in a DNS database. Using nslookup, you can manually check a domain's Sender Policy Framework (SPF) record as follows:

  1. Open Command prompt (Start > Run > cmd)
  2. Enter the domain or hostname, a space, and then nslookup -type=txt.
  3. If there is an SPF record, the outcome would be like v=spf1 ip4:207.171.160.0/19 -all.
  4. If there are no results or v=spf1 properties, there is an issue with retrieving the records.

5. Where is the SPF record kept?

An SPF record is stored in the DNS zone file.

6. How to check SPF records in Linux?

  1. Open Command prompt (Start > Run > cmd)
  2. Enter the domain or hostname, a space, and then nslookup -type=txt.
  3. If there is an SPF record, the outcome would be like v=spf1 ip4:207.171.160.0/19 -all.
  4. If there are no results or v=spf1 properties, there is an issue with retrieving the records.

7. How do I know if my SPF record is valid/correct?

  • Go to the SPF checker.
  • Enter the domain name and press validate button.
  • The result will display the validity of your SPF record.

8. What happens if the SPF record is invalid?

When the Sender Policy Framework (SPF) validation for a sender's domain fails, an SPF validation error may occur. Email administrators should confirm that the SPF records for their domain are properly configured at the domain registrar to avoid such problems. SPF records must be properly formatted.

9. How to format an SPF record for my domain?

  1. Gather IP addresses used to send the email.
  2. Make a list of your sending domains.
  3. Create your SPF record.
  4. Publish your SPF to DNS.
  5. Test your SPF record with an SPF check tool.

10. How to find my SPF syntax?

If your SPF record has syntax errors, the receiving server immediately returns a PermError without further evaluation. Your emails will fail SPF authentication and might not reach the inbox. To check if your SPF record has any syntax errors, use DMARCLY's free SPF Record Checker.

11 . How to avoid SPF lookup failure?

The SPF delegation tool can be used to address the "Too many lookups" problem and replace your current policy with the one offered by the DNS delegation tool. Every time one of the included ESPs modifies its entries, the DNS delegation tool will update the SPF record.

12 . What is the SPF lookup limit?

The maximum number of SPF lookups is 10. This limit helps reduce the number of resources mailbox providers use when checking SPF records. Exceeding these limits can cause SPF checks to fail.

13 . What are the reasons for exceeding SPF lookup limit?

  • Forgetting the DNS lookup limit.
  • Using multiple SPF records.

14 . Why impose the SPF DNS lookup limit?

The SPF specification caps DNS lookups at ten per request. This cap reduces the resources mailbox providers must use to check SPF records. So, the limit enforced upon the SPF records will reduce the burden on these servers.

15 . What happens if the SPF DNS lookup limit is exceeded?

The SPF perm error "Too many DNS lookups" is returned if the receiving email server discovers more than 10 DNS querying modifiers in the sender's domain SPF. Hence, the sent email might not make it to the inbox.

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