Email Header
Email headers are RFC-compliant metadata fields that accompany every email message. Headers include routing information (From, To, Subject, Date), authentication data (DKIM signatures, SPF results), delivery information (Received headers), and custom fields set by sending systems.
Key Email Headers
Common headers include From (sender address), To (recipient addresses), Subject (email title), Date (sent timestamp), Message-ID (unique identifier), Reply-To (address for responses), and List-Unsubscribe (for easy opt-out). Authentication headers include DKIM-Signature, Received-SPF, and Authentication-Results.
Related Terms
Email Authentication
Technical standards (SPF, DKIM, DMARC) that verify an email was sent by an authorized source.
SPF (Sender Policy Framework)
Tells receiving servers which IPs can send email for your domain.
DKIM (DomainKeys Identified Mail)
Adds a digital signature to emails proving they haven't been tampered with.
DMARC (Domain-based Message Authentication)
Tells email receivers how to handle messages that fail SPF or DKIM checks.
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