Email security concepts
DMARC domain
The domain name where the DMARC record is published in DNS (omitting the _dmarc. prefix), defining the authentication rules and reporting destination for emails sent under that domain or its subdomains.
Also known as: DMARC policy domain
Envelope from
Envelope from is the technical sender email address used during transport and routing (similar to the sender on a physical mail envelope). Delivery issues, bounces, or out-of-office notifications are sent back to it. It is evaluated in SPF.
Also known as: Return path, Bounce address, Mail from, RFC5321.MailFrom
Envelope to
Envelope to is the technical destination address used by mail servers to route and deliver the message. It can differ from visible To, Cc, or Bcc recipients.
Also known as: Final recipient, RCPT TO, RFC5321.RcptTo
Header from
Header from is the visible email address displayed to the end-user in their email client (like Outlook, Thunderbird). It indicates who the message claims to be from. It is the primary mail address evaluated by DMARC.
Also known as: Friendly from, RFC5322.From
Message group
A collection of emails evaluated over a reporting period by a receiving provider that share identical characteristics, including the same sending IP, DMARC domain, and SPF and DKIM results.
Also known as: DMARC aggregate report record
Receiving provider
A receiving provider is the email platform or infrastructure organization that accepts mail sent on behalf of a domain and generates DMARC reports.
Also known as: Receivers, Reporters, Reporting organizations, Report generator
Sending provider
A sending provider is the third-party service, server, platform, or infrastructure entity authorized (or attempting) to send mail on behalf of a domain.
Also known as: Sender, Source, Sending source
Sending IP
The IP address of the specific computer or mail server that sent the email to the receiving provider.
Also known as: Source IP address