Message header

As explained in AI for Everyday IT

An email header is metadata attached to an email that records addressing, authentication, routing, and other delivery information.

An email message header is a block of delivery and authentication information that helps investigate suspicious messages. When an unexpected email requests a link click or sensitive information, inspect its headers and source rather than trusting its appearance. section 7.1.3

Use headers for a practical phishing check:

• Open the message source or header information in your email client. section 7.1.3
• Copy the header and source text into an approved AI service for analysis. section 7.1.3
• Review authentication results such as SPF, DKIM, and DMARC, while treating the result as guidance rather than automatic proof. section 7.1.3

Finding and analyzing headers

In Outlook for Mac, right-click the message and choose View Source. In Outlook for PC, open the message in a new window, select File, then Properties. Paste the resulting text into M365 Copilot and ask whether the email is a phishing attempt. section 7.1.3

Figure 7.2 Finding the source text and headers of an email in Outlook for Mac and PC

Shows where Outlook for Mac and PC expose message source and header information. section 7.1.3

How AI for Everyday IT covers it

How deep it goes

Provides retrieval steps and authentication checks, but does not require readers to interpret raw header text themselves.

Examples

Uses Outlook Mac and PC retrieval paths, pasted source text, and an AI phishing-analysis request.

What it assumes

Assumes access to an email client and teaches retrieval without requiring header-format expertise.

What you can do after

Diagnose suspicious email with an email client and AI-assisted checks of source text and authentication results.

How it connects

Connects email headers with phishing, email source code, SPF, DKIM, DMARC, and M365 Copilot.

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Related concepts

• HTTP headercontrasts with · An HTTP header is a named metadata field in an HTTP request or response that conveys information about the message or directs its processing.
• headerkind of · A header is the leading record or portion of a structured file or data object that identifies or describes its format, contents, or fields.
• headercontrasts with · An IPv4 header is the protocol metadata placed before an IPv4 packet's payload, including fields that describe packet handling and delivery.

This explainer was generated by Manning's knowledge graph from the text of AI for Everyday IT. The section links point to the parts of the book it draws on.