# 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](https://dmarced.eu/en/learn/email-security/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](https://dmarced.eu/en/learn/email-security/dmarc/overview).

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](https://dmarced.eu/en/learn/email-security/dmarc/xml-report).

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