email-toolbox-wiki/parked-domain-how-to.md

• Introduction
• What is a parked domain?
• Domain without e-mail
  • Null MX
  • DMARC
  • DKIM
  • SPF
• Domain without a website

Table of contents generated with markdown-toc

Introduction

This how-to is created by the Dutch Internet Standards Platform (the organization behind internet.nl) and is meant to provide practical information and guidance on explicitly configuring a parked domain not to use e-mail.

What is a parked domain?

Domain parking is the registration of an Internet domain name without that domain being associated with any services such as e-mail or a website.

Domain without e-mail

If a domain is not using e-mail it is recommended to use the following settings.

Null MX

Explicitly configure an 'empty' MX record according to RFC7505 .

example.nl IN MX 0 .

DMARC

Set DMARC policy to reject mails, but allow reporting to take place. This helps detecting activity related to your domain.

_dmarc IN TXT "v=DMARC1; p=reject; rua=mailto:rua@example.nl; ruf=mailto:ruf@example.nl

DKIM

When using a wildcard selector to set an empty public key, you indicate that all previously used keys are revoked and must be considered unreliable. You can also use this to explicitly signal that a domain is not configured to use e-mail. However, according to the RFC the absence of a selector / public key (e.g. as a result of deleting the entire DKIM resource record) is semantically equal to a resource record with an empty public key. This means that both approaches should be treated similar by the receiving mail server.

*._domainkey IN TXT "v=DKIM1; p="

SPF

Set an an empty policy (not mentioning any ip-adresses or hostnames which are allowed to send mail) and a hard fail.

example.nl IN TXT "v=spf1 –all"

Domain without a website

Apply the following settings to domains not using a website.

• Don't use an A or AAAA record for parked domains.
• Don't redirect from a parked domain to the used domain, since this encourages users to keep using the parked domain name. If a redirect is desirable, make sure to use the proper redirect order in order for HSTS headers to remain effective:
  1. redirect from HTTP to HTTPS on the same (sub)domain.
  2. when using HTTPS, redirect to another (sub)domain.