What Are Email Headers?
Understanding email headers and their importance
Table of Contents
What Are Email Headers?
Email headers are metadata fields that contain information about an email message, including sender and recipient addresses, subject, date, routing information, authentication results, and delivery details. Headers are added by email servers and clients as emails are sent and received, creating a complete record of the email's journey.
Important headers include From, To, Subject, Date, Received, Message-ID, Authentication-Results, and SPF/DKIM/DMARC headers. Headers are essential for troubleshooting delivery issues, verifying authentication, tracking email routing, and understanding email delivery problems.
Analyze email headers using our email header analyzer to troubleshoot delivery issues, verify authentication (SPF, DKIM, DMARC), track routing, and check RFC compliance.
Header Structure
Header Format
Email headers follow a simple format: Header-Name: Header Value
Multiple Headers
Emails contain multiple headers, each providing different information about the message.
Header Order
Headers are typically ordered with basic information first (From, To, Subject), followed by routing information (Received headers), and technical details (authentication, MIME).
Received Headers
Multiple Received headers show the email's path through different servers, with the most recent server first.
Important Headers
Basic Headers
- From: Sender email address and name
- To: Primary recipient addresses
- Subject: Email subject line
- Date: When email was sent
- Message-ID: Unique message identifier
Routing Headers
- Received: Server routing information (multiple entries)
- Return-Path: Bounce address
- Reply-To: Reply address
Authentication Headers
- Authentication-Results: SPF, DKIM, DMARC results
- Received-SPF: SPF authentication result
- DKIM-Signature: DKIM signature information
- ARC-Authentication-Results: ARC authentication
MIME Headers
- Content-Type: Email content type and encoding
- MIME-Version: MIME protocol version
Header Information
Email headers provide valuable information for various purposes:
1. Delivery Tracking
Received headers show the email's path through servers, helping track delivery and identify delays.
2. Authentication Verification
Authentication headers show SPF, DKIM, and DMARC results, verifying email authenticity. Check authentication using our email authentication checker.
3. Troubleshooting
Headers help diagnose delivery issues, identify server problems, and understand email routing.
4. Security Analysis
Headers reveal sender information, routing paths, and authentication status for security analysis.
5. Spam Analysis
Headers help identify spam characteristics, routing anomalies, and authentication failures.
Extracting Headers
Extracting email headers is essential for troubleshooting and analysis:
Why Extract Headers
- Troubleshoot delivery issues
- Verify authentication results
- Track email routing
- Analyze delivery delays
- Security investigation
Extraction Methods
Use our email header analyzer to extract and analyze headers from email files (.eml, .msg) or email source code with comprehensive analysis capabilities.
Header Analysis
After extraction, analyze headers for:
- Authentication results (SPF, DKIM, DMARC)
- Routing information (Received headers)
- Delivery timing and delays
- Server information
- Security indicators
