SPF alignment, short for Sender Policy Framework alignment, is a requirement under DMARC (Domain-based Message Authentication, Reporting, and Conformance) that makes sure the domain in the email's “From” address matches the domain authorized in the SPF record. This alignment improves email authentication and helps prevent spoofing.
What Is SPF Alignment?
SPF alignment verifies that the domain specified in the visible “From” header of an email aligns with the domain listed in the SPF record used for authentication.
Under DMARC rules, an email can only pass authentication if either SPF or DKIM (DomainKeys Identified Mail) passes and aligns with the “From” domain.
There are two types of SPF alignment:
- Relaxed alignment: The organizational domain matches (e.g., From: newsletter.example.com aligns with SPF domain example.com).
- Strict alignment: The domains must match exactly (e.g., From: example.com matches SPF domain example.com, but not sub.example.com).
SPF alignment is one of the key elements for implementing DMARC policies effectively.
How Does SPF Alignment Work?
The SPF alignment process works as follows:
- SPF check: The recipient’s mail server verifies that the sending IP address is authorized in the domain’s SPF record.
- Domain comparison: The domain used in the “Mail From” (envelope sender) is compared with the domain in the visible “From” header.
- Alignment validation: If the domains align according to DMARC policy (relaxed or strict), the message passes SPF alignment.
- DMARC enforcement: If alignment fails, the message may be quarantined or rejected based on the DMARC policy.
Why Is SPF Alignment Important?
SPF alignment matters because:
- Prevents domain spoofing: Ensures attackers cannot pass SPF checks using a different domain.
- Strengthens email security: Works with DKIM alignment to enforce DMARC compliance.
- Improves deliverability: Authenticated and aligned emails are more likely to land in the inbox.
- Supports brand protection: Reduces phishing attacks targeting customers using your domain.
Without SPF alignment, even emails that technically pass SPF may fail DMARC, leading to deliverability issues.
Common Use Cases
SPF alignment is important for:
- DMARC implementation: Required for enforcing DMARC policies.
- Transactional email systems: Making sure notifications and receipts align with the domain identity.
- Email marketing: Maintaining trust and brand consistency in large-scale campaigns.
- Third-party senders: Configuring alignment when using external platforms to send emails on behalf of a brand.
Example scenario: A company using a marketing automation platform updates its SPF record to include the platform’s sending IPs and makes sure that the “From” domain aligns with the corporate domain for DMARC compliance.
FAQs About SPF Alignment
Does SPF alignment mean SPF authentication?
No. SPF authentication checks IP authorization, while alignment ensures the domain matches the “From” address under DMARC rules.
What happens if SPF passes but alignment fails?
The email may still fail DMARC unless DKIM passes and aligns with the domain.
How do I set SPF alignment to strict mode?
By configuring the DMARC policy with aspf=s (strict) instead of aspf=r (relaxed).
