'mailserver', '.intranet', broken by design
The use of invalid TLDs for internal networks was always a broken concept. Architects and network engineers would just create anew one when it suited them, ignoring the hierarchical nature of domains and sub-domains, ignoring the maximum number of domains in search paths, adding pointless layers of complexity, and pretending it added security because 'this will never be a valid external TLD'.
It's a hack created by people who simply shouldn't have had the power to create it.
Biting the hand that feeds IT
