Generate and validate SPF (Sender Policy Framework) records to prevent email spoofing.
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Generate and validate SPF (Sender Policy Framework) records to prevent email spoofing
Understanding SPF records and email authentication best practices
This page provides original, human-reviewed information about generating SPF records, walking through mechanism selection, third-party sender includes, and keeping records within DNS lookup limits.
SPF (Sender Policy Framework) records are DNS TXT records that specify which mail servers are authorized to send emails on behalf of your domain. They help prevent email spoofing and improve email deliverability.
Includes SPF record from another domain (most common for email providers)
Authorizes specific IPv4 addresses or ranges
Authorizes all servers listed in the domain's MX records
SPF records are limited to 10 DNS lookups. Exceeding this limit causes SPF validation to fail.
Solution: Use SPF flattening or reduce include: mechanisms.
Having multiple SPF records in DNS causes all of them to be ignored.
Solution: Combine all SPF mechanisms into a single TXT record.
SPF records longer than 255 characters may not be processed correctly.
Solution: Use SPF flattening or optimize mechanism syntax.
These are qualifiers that determine what happens to emails from unauthorized servers:
SPF record changes typically propagate within 24-48 hours, but can take up to 72 hours depending on DNS TTL settings. Most changes are visible within a few hours.
No, you can only have one SPF record per domain. Having multiple SPF records will cause all of them to be ignored. If you need to authorize multiple email sources, combine them into a single SPF record.
SPF records are limited to 10 DNS lookups during validation. Mechanisms like 'include:', 'a', 'mx', 'exists', and 'redirect' count toward this limit. Exceeding 10 lookups causes SPF validation to fail.
Use 'include' for email service providers (like Google, Microsoft) as their IP addresses can change. Use 'ip4' only for your own mail servers with static IP addresses.
You can test SPF records using:
SPF records longer than 255 characters may be truncated or ignored by some email servers. Use SPF flattening services or optimize your record by removing unnecessary mechanisms to stay under the limit.
Our tools are designed to be intuitive, but if you need assistance, we're here to help.
Professional-grade email and DNS diagnostic tools trusted by IT professionals worldwide.
