Authentication
What is Header From (From: Header)?
The visible From address recipients see, and the identity DMARC alignment is measured against.
The header From is the From field in the message headers shown in the recipient's mail client, as defined by RFC 5322. It is distinct from the envelope sender used during SMTP transfer. DMARC requires that a passing SPF or DKIM domain align with the header From domain, making this address the anchor for domain-based authentication.
Why it matters for cold email
Spoofing the header From is the abuse DMARC exists to stop, so cold email must send from a From domain that aligns with its authenticated domains. Using a consistent, recognizable header From domain also builds recipient trust and supports a clean sender reputation.
Related terms
Stop guessing at deliverability.
Scheduler Zero handles authentication, warmup, and sender reputation so your cold email lands in the inbox, not the spam folder.