SPF Implementation Guide

Secure your email with Sender Policy Framework

Learn how to implement and manage SPF (Sender Policy Framework) records to prevent email spoofing and improve deliverability.

What is SPF?

SPF (Sender Policy Framework) is an email authentication method that allows domain owners to specify which mail servers are authorized to send email on their behalf. It helps prevent email spoofing and is a key component of DMARC authentication.

Implementation Steps

Step 1 of 4
DNS Setup🔧(5 min)

1. Identify Email Sources

Document all sources that send email on behalf of your domain:

  • Your mail servers (MX records)
  • Third-party email services (e.g., SendGrid, Mailchimp, Google Workspace)
  • Marketing platforms
  • Cloud services (e.g., AWS SES, Azure)
  • Any other authorized senders

This inventory is crucial for creating a complete SPF record.

Step 2 of 4
Record Creation📝(10 min)

2. Create SPF Record

Create your SPF record with all authorized senders:

v=spf1 include:_spf.google.com include:sendgrid.net ip4:192.0.2.0/24 ~all

Common mechanisms:

  • include:domain.com - Include another domain's SPF record
  • ip4:192.0.2.0/24 - Authorize IP addresses (IPv4)
  • ip6:2001:db8::/32 - Authorize IP addresses (IPv6)
  • a - Authorize A records
  • mx - Authorize MX records
  • ~all - Soft fail for all other sources
  • -all - Hard fail for all other sources
Step 3 of 4
Testing🧪(5 min)

3. Test Your SPF Record

Use our SPF validation tool to test your configuration:

Test your SPF record to ensure it's valid and stays within the 10-lookup limit:

Test Your SPF Record
Step 4 of 4
Optimization⚙️(15 min)

4. Optimize Lookup Count

Ensure your SPF record stays within the 10-lookup limit:

  • Replace include: mechanisms with direct ip4: or ip6: where possible
  • Remove unnecessary include statements
  • Use SPF flattening services if needed
  • Consolidate multiple includes from the same provider

Each include, a, mx, and exists mechanism consumes DNS lookups. IP-based mechanisms (ip4, ip6) do not.

Best Practices

Stay within 10 lookups

RFC 7208 limits SPF records to 10 DNS lookups. Exceeding this limit causes permerror.

Use only one SPF record

Only one SPF record is allowed per domain. Multiple records will cause SPF to fail.

Prefer IP addresses over includes

Use ip4/ip6 mechanisms instead of include when possible to reduce lookup count.

Start with soft fail (~all)

Use ~all initially to monitor impact before switching to -all (hard fail).

Test before deploying

Always test your SPF record with validation tools before making DNS changes.

Keep record under 512 characters

While not strictly required, keeping records under 512 characters is recommended for compatibility.

Common Issues and Solutions

Lookup Limit Exceeded

If your SPF record requires more than 10 DNS lookups, receiving servers will return a permerror. Replace include mechanisms with direct IP addresses where possible, or use SPF flattening services.

Multiple SPF Records

Only one SPF record is allowed per domain. If you have multiple TXT records starting with "v=spf1", combine them into a single record.

Syntax Errors

Common syntax errors include invalid mechanism names, missing colons in include statements, and invalid IP address formats. Use validation tools to identify and fix these issues.

Test Your Implementation

Use our SPF testing tool to verify your configuration and lookup consumption:

Test Your SPF Configuration