People without a basic understanding of RFC 2606 have been using a From or Reply-To address of
firstname.lastname@example.org, and surprise!, that domain exists.
This implies not just job incompetence, but a manner so cavalier and naïve that the person responsible didn't even consider typing
donotreply.com into a browser.
This is a level of technical malpractice worthy of termination, IMO.
Remember, the people that designed the Internet were generally pretty clever folks. If you need a phony domain name (akin to a 555 phone number), for example, there's a pretty good chance someone has set aside a few of those.