Email Header
An email header is the section of an email message that contains metadata about the message, including the sender, recipient, subject, date, routing path, and authentication results. Headers are mostly hidden from users but are essential for email delivery, troubleshooting, and security analysis.
What You Need to Know
Routing Information
Contains Received headers showing the path the email took from sender to recipient through various servers.
Authentication Results
Records SPF, DKIM, and DMARC check results, providing transparency into authentication status.
Troubleshooting Tool
Analyzing headers helps diagnose delivery issues, identify spoofing, and trace message routing.
Key Email Header Fields
Every email contains dozens of header fields, most of which are hidden by default in email clients. The most familiar headers are From, To, Subject, and Date. Beyond these, technical headers like Message-ID, Received, Return-Path, and Authentication-Results provide critical information about the message's origin and journey.
The Received headers are particularly important for troubleshooting. Each mail server that handles the message adds a Received header, creating a traceable path from sender to recipient. Reading these headers from bottom to top reveals the chronological journey of the email. DKIM-Signature and Authentication-Results headers show whether the email passed security checks.