In [this question][1], the asker wanted to obfuscate their domain name. They did so by using a domain owned by a public well-known company. (I edited the question to use example.com instead.) I've also seen several other questions where the asker has used e.g. `domain.com`, `mydomain.com` and similar names, rather than the RFC-blessed `example.com`. 

There's been a [feature request earlier][2] about creating a mark-up for obfuscation of domain names. However, until/unless it's been implemented it might be helpful to have a section in "How to ask questions" that deals with "how to obfuscate domain names properly".

Here's a suggestion for text to be used:

> Please don't obfuscate your actual domain name unless absolutely necessary. In any question relating to DNS and/or email issues, the people trying to help you may need to be able to look at your DNS records in order to help you. If, despite this, you feel it necessary to use a fake domain name, please use the standard name `example.com`. Never use any domain name that is not related to your question.


  [1]: https://serverfault.com/questions/565068/postfix-not-recieving-mail-from-actual-email-but-does-from-sendmail
  [2]: https://meta.serverfault.com/questions/1244/obfuscating-domain-names