Back when it was first discovered that spammers were scraping WHOIS registrations for email addresses, private registration of domains became popular among legitimate businesses. Unfortunately, like so many other things, registering your domain privately (meaning that your domain registration information is essentially cloaked, and anonymous to the world) has been adopted and thus ruined by the spammers, phishers, and malware pushers of the world. Now, if you are a legitimate sender, having a privately registered domain will hurt your email deliverability.
