Glossary
The email-authentication vocabulary, in plain English.
What is the Return-Path? (envelope from)
The hidden envelope address that receives your bounces and decides SPF. What it is, who sets it, and why it rarely matches the From your reader sees.
What is the Header From address?
The From address people actually see, and the one DMARC exists to protect. How it differs from the envelope sender and why both alignment checks compare against it.
What is a DKIM selector?
The s= label that picks which signing key a receiver looks up. How a selector maps to a DNS record, why vendors each want their own, and how to see yours.
What is DMARC alignment?
Why an SPF or DKIM pass is not enough on its own: the domain-matching rule that decides whether a pass counts for DMARC, in relaxed and strict modes.
What is a DMARC aggregate report? (RUA)
The daily XML receipts mailbox providers send about mail using your domain. What they contain, what they deliberately leave out, and who sends them.
What is a DMARC forensic report? (RUF)
The per-message failure sample almost no provider sends anymore. What ruf= asks for, why privacy killed it, and why aggregate reports do the real work.
What is an organizational domain?
The registrable root that DMARC falls back to when a subdomain has no policy of its own. How the Public Suffix List decides it and why it matters for alignment.
What is a DMARC record?
The one-line TXT record at _dmarc that publishes your policy and reporting addresses. Its anatomy, the tags that matter, and a safe record to start with.
What is a DMARC policy? (p=none, quarantine, reject)
What each policy level actually tells receivers to do with failing mail, what none is for, and how domains climb to reject without losing real mail.
What does quarantine mean in email?
Where quarantined mail actually goes: the spam folder for most receivers, an admin hold for some. What p=quarantine asks for and how it differs from reject.
What is email spoofing?
How anyone can put your domain in the From line of mail you never sent. What spoofing is, how it differs from a hacked account, and what actually stops it.
What is a Verified Mark Certificate? (VMC)
The certificate that proves you own the logo your BIMI record publishes. Who issues VMCs, what they cost, and when you actually need one.
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