Email Header Analyzer

The Email Header Analyzer is a free online tool that decodes and analyzes email headers to reveal critical information about the origin, path, and authenticity of any email message. Email headers contain a wealth of metadata that most users never see, including the sender's IP address, the complete delivery path through multiple mail servers, authentication results, and timestamps that can help identify suspicious activity.

Email headers are essentially the invisible paperwork that accompanies every email you send or receive. Just like a physical letter has an envelope with return and delivery addresses, an email has headers that contain information about where it came from, where it's been, and whether it passed security verification. This tool makes that hidden information visible and understandable.

Understanding email authentication is crucial in today's threat landscape. SPF (Sender Policy Framework) is a security mechanism that allows domain owners to specify which mail servers are authorized to send email on their behalf. When an email arrives, the receiving server checks if the sending server is listed in the domain's DNS records. If it matches, the email passes SPF validation. This helps prevent spammers from sending emails that appear to come from your domain.

DKIM (DomainKeys Identified Mail) adds a cryptographic digital signature to emails, similar to a wax seal on a letter. When a domain configures DKIM, it generates a private key that signs outgoing emails, and recipients use a public key published in DNS to verify the signature. If the signature validates, it proves the email hasn't been modified in transit and actually came from the claimed domain. This protects against man-in-the-middle attacks where someone might alter an email's content.

DMARC (Domain-based Message Authentication, Reporting, and Conformance) is the policy layer that ties SPF and DKIM together. It tells receiving servers what to do if an email fails authentication checks. A DMARC policy can instruct receivers to reject or quarantine emails that fail, and it provides reporting so domain owners can see who's trying to send email on their behalf. This creates a powerful defense against email spoofing and phishing attacks.

The "Received" headers in an email form a chain showing each mail server the message passed through, from the original sender to the final recipient. By analyzing this chain, you can trace an email's journey, identify where delays occurred, and spot suspicious routing that might indicate the email took an unusual path. Each server adds its own Received header with a timestamp, creating a chronological breadcrumb trail.

Email header analysis is invaluable for multiple use cases. Security professionals use it to investigate phishing attempts and trace spam back to its source. IT administrators troubleshoot delivery issues by identifying which server is causing delays or rejections. Journalists and investigators verify the authenticity of communications. And everyday users can confirm an email actually came from who it claims to be before trusting its contents.

This tool performs all analysis entirely in your browser. It extracts and parses email headers without making any DNS lookups or server queries, ensuring your analysis remains private and doesn't trigger any network requests to external servers. This makes it safe to use with sensitive or confidential emails.

Common issues detected through header analysis include spoofed sender addresses where the From field doesn't match the actual source, failed SPF or DKIM checks indicating the email may be fraudulent, suspicious routing through unexpected countries or unknown servers, unusual delays suggesting delivery problems, and configuration errors that might explain why emails aren't arriving. The analyzer highlights all these findings with clear explanations.