Email Header Analyzer

Email headers are metadata attached to every email message that contain detailed information about the message's origin, routing, and delivery. They are typically hidden from view in email clients but contain valuable technical information.

Headers include information such as the sender and recipient addresses, the subject line, timestamps, the servers the message passed through, and authentication results. Each time an email passes through a mail server, a new "Received" header is prepended, creating a trail of the message's journey from sender to recipient.

Analyzing email headers is essential for troubleshooting delivery issues, verifying the authenticity of a message, identifying spam or phishing attempts, and understanding network delays in email delivery.

Email headers are read from bottom to top. The bottom-most "Received" header represents the first server that handled the email (closest to the sender), and the top-most "Received" header represents the last server (closest to the recipient).

Each "Received" header follows the general format: Received: from [sending-server] by [receiving-server] with [protocol]; [timestamp]

By comparing timestamps between consecutive hops, you can identify where delays occur in the delivery chain. Large gaps may indicate server congestion, greylisting, content scanning, or network issues.

Key headers to look for include From, To, Subject, Date, Message-ID, Return-Path, Authentication-Results, and X-Spam-Status.