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DMARC

As explained in AI for Everyday IT

DMARC is an email-authentication standard that lets a domain publish policies for handling messages that fail sender-authentication checks and receive reports about those checks.

DMARC is an email-authentication standard that tells receiving servers how to handle messages that fail authentication checks. It helps distinguish legitimate messages from possible phishing attempts. section 7.1.3

Email analysis can use DMARC alongside:

  • SPF, which checks whether the sending server is authorized for the domain. section 7.1.3
  • DKIM, which uses digital signatures to check that an email has not been tampered with. section 7.1.3
  • Email source text and headers, which provide authentication signals for investigation. section 7.1.3

Suspicious SharePoint message

An email claiming to come from SharePoint uses the domain sharepoint-docshare.com and shows an SPF SoftFail. These authentication problems support treating the message as a possible phishing attempt. section 7.1.3

How AI for Everyday IT covers it

How deep it goes
Defines DMARC’s receiving-server role and connects it to SPF and DKIM, but does not detail policy syntax or report handling.
Examples
Uses a suspicious SharePoint email, its source code, headers, and SPF SoftFail as investigation evidence.
What it assumes
Assumes access to email source text and headers while teaching the roles of SPF, DKIM, and DMARC.
What you can do after
Evaluate an email’s authentication signals and use them as evidence when judging possible phishing.
How it connects
Connects DMARC with SPF, DKIM, email headers, and phishing detection.
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Related concepts

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.