Header From vs Envelope From
The single most-confused topic in email auth. This page explains both headers, where SPF checks, where DMARC checks, and why a SPF-passing email can still fail DMARC.
| Scenario | Header From | Return-Path | SPF | DMARC |
|---|---|---|---|---|
| Direct send from your own MTA | you@yourdomain.com | you@yourdomain.com | Pass (your SPF lists your MTA IP) | Pass (aligned) |
| Send via ESP (no custom Return-Path) | you@yourdomain.com | bounce@esp.example.com | Pass (ESP's SPF lists its MTA) | Fail (Header From and Envelope From not aligned) |
| Send via ESP (custom Return-Path) | you@yourdomain.com | bounce@yourdomain.com | Pass (you CNAME to ESP's SPF) | Pass (aligned via custom Return-Path) |
| Forwarded through mailing list | original@sender.com | list@list-host.com | Fail (list-host MTA not in original sender's SPF) | Fail unless ARC seal present |
| Phishing. spoofed From | ceo@yourcompany.com | attacker@evil.com | Pass (evil.com's SPF allows the attacker's MTA) | Fail (not aligned, p=reject blocks it) |
SPF checks the Envelope From (Return-Path). DMARC requires the Envelope From domain to align with the Header From domain. Most ESP-related DMARC failures are alignment problems, not SPF problems.
You know the rule. See where you sit against it.
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See your numberReference page with worked examples: a forwarded email, a marketing platform send, a bounce, and a phishing attempt, each annotated to show what's in From vs Return-Path and which checks pass.
Anytime SPF is passing but DMARC isn't (or vice versa). The answer is almost always a Header From / Envelope From alignment mismatch.
FAQ
Why does SPF pass but DMARC fail?+
SPF checks the Envelope From (Return-Path). DMARC requires the Envelope From domain to align with the Header From domain. ESPs that send with their own Return-Path break that alignment unless you set up custom Return-Path.
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Articles, glossary entries, and other tools on the same topic.
Nate built Outsolvi after watching every email-tracking tool he had ever used lie to him about opens. Outsolvi runs Tier 1 to 5 confidence scoring on every open, native in Outlook and Gmail, so the number on the dashboard is one a rep can actually act on.
We update these pages when the underlying mechanics change. new mailbox-provider rules, new tracker behavior, new measurement gaps. The dates above are real revisions, not auto-touches.