Free Email Header Analyzer

Understanding Email Headers

Email headers are the hidden metadata attached to every email message. While most email clients only show you the From, To, Subject, and Date fields, the full headers contain a wealth of technical information about how the message was created, routed, and delivered. This includes server hostnames, IP addresses, authentication results, spam scores, and precise timestamps for every server hop along the delivery path.

When an email is sent, it passes through multiple mail servers before reaching the recipient's inbox. Each server adds a "Received:" header to the top of the message, creating a chronological trail when read from bottom to top. By analyzing these hops, you can identify where delays occur, which servers handled the message, and whether the email was routed through unexpected infrastructure -- which can be a sign of spoofing or misconfiguration.

Header analysis is an essential skill for email administrators, deliverability specialists, and security professionals. It helps diagnose why emails land in spam, verify that authentication records (DKIM, SPF, and DMARC) are correctly configured, and investigate suspicious messages. If you suspect deliverability issues, also check whether your sending IP appears on any email blacklists.